High potency recombinant antibodies and method for producing them

ABSTRACT

High potency antibodies, including immunologically active fragments thereof, having high kinetic association rate constants and optional high affinities are disclosed, along with methods for producing such antibodies. The high potency antibodies disclosed herein are of either the neutralizing or non-neutralizing type and have specificity for antigens displayed by microorganisms, especially viruses, as well as antigenic sites present on cancer cells and on various types of toxins, and the products of toxins. Processes for producing high potency neutralizing antibodies and increasing the potency of already existing neutralizing antibodies are also described. Methods of using said antibodies in the prevention and/or treatment of diseases, especially diseases induced or caused by viruses, are disclosed.

[0001] This application claims priority of U.S. Provisional ApplicationSerial No. 60/186,252, filed Mar. 1, 2000, the disclosure of which ishereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to high potency antibodies, methodsof increasing antibody potency and to methods of using such antibodiesfor prevention and treatment of diseases.

BACKGROUND OF THE INVENTION

[0003] Antibodies have been, and are currently being, developed for theprevention and treatment of various diseases, especially those caused byinfectious microorganisms, such as the viruses.

[0004] One approach has been the development of antibodies, especiallyneutralizing monoclonal antibodies, some with high specific neutralizingactivity. One drawback to this approach has been the need to producehuman antibodies rather than those of mouse or rat and thus minimize thedevelopment of human anti-mouse or anti-rat antibody responses, whichpotentially results in further immune pathology.

[0005] An alternative approach has been the production of human-murinechimeric antibodies in which the genes encoding the mouse heavy andlight chain variable regions have been coupled to the genes for humanheavy and light chain constant regions to produce chimeric, or hybrid,antibodies. For example, a humanized anti-RSV antibody has been preparedand is currently being marketed. [See: Johnson, U.S. Pat. No. 5,824,307]

[0006] In some cases, mouse complementarity determining regions (CDRs)have been grafted onto human constant and framework regions with some ofthe mouse framework amino acids (amino acids in the variable region ofthe antibody but outside of the CDRs) being substituted forcorrespondingly positioned amino acids from a human antibody of likespecificity to provide a so-called “humanized” antibody [see, forexample, Queen, U.S. Pat. Nos. 5,693,761 and 5,693,762]. However, suchantibodies contain intact mouse CDR regions and have met with mixedeffectiveness and exhibiting affinities often no higher than 10₇ to 10₈M⁻¹.

[0007] The production of high potency antibodies (i.e., antibodies withhigh biological activity, such as antigen neutralizing ability),including antibodies with ultra high affinity for the target antigen,would be desirable from the point of view of both the neutralizingability of such an antibody as well as from the more practical aspectsof requiring less antibody in order to achieve a desirable degree ofclinical effectiveness, thereby cutting costs of use.

[0008] Antibody affinity is measured by the binding constant of theantibody for a particular antigen, and such binding constant is oftencalculated by the ratio of the rate constant for antibody-antigencomplex formation (referred to as the “k_(on)” value) to the rateconstant for dissociation of said complex (the “k_(off)” value). Inaccordance with the present invention, it has been determined thatantibody potency is a function of the k_(on) value, irrespective ofspecificity. The present invention thus provides a solution to problemsof achieving high antibody potency in that the higher the k_(on) value,the higher the potency of the antibody thereby affording high potencyantibodies and a method for producing them.

BRIEF SUMMARY OF THE INVENTION

[0009] In accordance with an aspect of the present invention, there areprovided high potency antibodies useful in the treatment and/orprevention of a disease. In another aspect, the potency of an antibodyis increased by increasing the rate constant for antigen-antibodycomplex formation (the “k_(on)” value).

[0010] In one aspect, the present invention relates to high potencyantibodies, other than vitaxin, including immunologically activeportions, fragments, or segments thereof, having a k_(on) of at least2.5×10⁵ M⁻¹ s⁻¹, preferably at least about 5×10⁵ M⁻¹ s⁻¹, and mostpreferably at least about 7.5×10⁵ M⁻¹ sec⁻¹. antibodies may also have ahigh affinity (at least about 10⁹ M⁻¹).

[0011] In another aspect, the present invention relates to high potencyneutralizing antibodies, including immunologically active portions,fragments, or segments thereof, having a k_(on) of at least 2.5×10⁵ M⁻¹s⁻¹, preferably at least about 5×10⁵ M⁻¹ s⁻¹, and most preferably atleast about 7.5×10⁵ M⁻¹ sec⁻¹. Such antibodies may also have a highaffinity (at least about 10⁹ M⁻¹).

[0012] It is a further object of the present invention to providemethods for increasing the potency of neutralizing antibodies byincreasing the k_(on) value with respect to a given antigen withoutchanging the epitope to which the antibody binds.

[0013] It is a still further object of the present invention to providea means of screening antibodies for properties that will insure highpotency with respect to a desired antigen, said potency being at least2- to 10-fold over known antibodies.

[0014] More specifically, it is an object of the present invention toproduce antibodies having k_(on) values at least as high as 2.5×10⁵ M⁻¹sec⁻¹, preferably at least 5×10⁵ M⁻¹ sec⁻¹, and most preferably as highas 7.5×10⁵ M⁻¹ sec⁻¹.

[0015] It is also an object of the present invention to provide highaffinity, high potency antibodies having high specificity toward one ormore antigens exhibited by an infectious microorganism (or microbe),especially one that causes infection of the respiratory system, mostespecially viruses.

[0016] In one embodiment, the present invention provides antibodieshaving substantially the variable chain framework (FR) regions of theantibody disclosed in FIG. 1 (with the same specificity as thisantibody) but wherein the polypeptide structures contain one or moreamino acid differences in one or more of the CDRs (or complementaritydetermining regions) thereof. In a preferred embodiment, the antibodiesof the present invention will differ from the antibody of FIGS. 1 or 2(hereafter, the “basic structure” or “reference structure”) only in thesequences of one or more of the CDRs, including L1, L2, L3, H1, H2 andH3. One preferred sequence is shown in FIG. 3.

[0017] It is another object of the present invention to providecompositions comprising the antibodies disclosed herein wherein saidantibodies are suspended in a pharmacologically acceptable carrier,diluent or excipient.

[0018] It is a still further object of the present invention to providemethods of preventing and/or treating diseases, such as is caused byviruses, especially respiratory syncytial virus, comprising theadministering to a patient at risk thereof, or afflicted therewith, of atherapeutically effective amount of a composition containing an antibodyas disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 shows the amino acid sequence of the light and heavy chainvariable regions of a high affinity monoclonal antibody whose potencycan be increased by the methods of the present invention. For referencepurposes, this antibody is the MEDI-493 antibody sequence disclosed inJohnson et al, J. Infect. Dis., 176:1215-1224 (1997). Here, the CDRregions are underlined while non-underlined residues form the frameworkregions of the variable regions of each polypeptide structure. In thisstructure, CDRs are derived from a mouse antibody while the frameworkregions are derived from a human antibody. The constant regions (notshown) are also derived from a human antibody. FIG. 1A shows the lightchain variable region (SEQ ID NO: 1) and FIG. 1B shows the heavy chainvariable region (SEQ ID NO: 2) of the light and heavy chains,respectively.

[0020]FIG. 2 shows the heavy and light chain variable regions for adifferent basic or reference polypeptide sequence. Again, CDR regionsare underlined. This sequence differs from FIG. 1 in the first 4residues of CDR L1 of the light chain, residue 103 of the light chainand residue 112 of the heavy chain. All of the high potency neutralizingFab structures of the present invention (CDR structures shown in Table2) use the framework sequences of this reference or basic structure.FIG. 2A shows the light chain (SEQ ID NO: 3) and FIG. 2B shows the heavychain (SEQ ID NO: 4) variable regions.

[0021]FIG. 3 shows the heavy (SEQ ID NO: 36) and light chain (SEQ ID NO:35) variable regions of a preferred embodiment of the present invention.This preferred antibody has several high k_(on) CDRs (or high potencyCDRs) present, which give rise to higher association rate constants(i.e., k_(on) ) than the basic or reference antibody of FIG. 2 and thushigher potency. This preferred antibody has the same framework aminoacid sequences as the sequence of FIG. 2 and, for purposes of thepresent disclosure, is denoted as “clone 15” in Tables 2 and 3, below.These sequences are readily generated by the methods disclosed herein,all of which are readily known to those of skill in the art. The kineticconstants were measured according to the procedure of Example 1 and thepotency determined as described in Example 2.

[0022]FIG. 4 shows a schematic diagram of the use of phage M13 forgeneration of Fab fragments in accordance with the present invention andusing a histidine tag sequence (6 histidine residues) to facilitatepurification.

[0023]FIG. 5 shows a schematic diagram for the screening procedure usedfor the antibodies of the present invention. “SPE” refers to a singlepoint ELISA. “H3-3F4” is a designation for clone 4 of Tables 2 and 3.

DETAILED SUMMARY OF THE INVENTION

[0024] In accordance with an aspect of the present invention, there areprovided high potency antibodies useful in the treatment and/orprevention of disease. In another aspect, the potency of an antibody isincreased by increasing the rate constant for antigen-antibody complexformation, which is referred to as the “k_(on)” value, by replacement ofCDR sequences of such antibody with high potency CDR sequences in theirplace.

[0025] In one aspect, the present invention relates to high potencyantibodies, other than vitaxin, including immunologically activeportions, fragments, or segments of said high potency antibodies, havinga k_(on) of at least 2.5×10⁵ M⁻¹ s⁻¹, preferably at least about 5×10⁵M⁻¹ s⁻¹, and most preferably at least about 7.5×10⁵ M⁻¹ sec⁻¹. Suchantibodies may also have a high affinity (at least about 10⁹ M⁻¹).

[0026] In one aspect, the present invention relates to high potencyneutralizing antibodies, including immunologically active portions,fragments, or segments thereof, having a k_(on) of at least 2.5×10⁵ M⁻¹s⁻¹, preferably at least about 5×10⁵ M⁻¹ s⁻¹, and most preferably atleast about 7.5×10⁵ M⁻¹ sec⁻¹. Such antibodies may also have a highaffinity (at least about 10⁹ M⁻¹).

[0027] The present invention is directed to methods of producingantibodies, neutralizing or non-neutralizing, having high potency, orbiological activity, preferably having an affinity of at least about 10⁰M¹, and having a k_(on) value of at least about 2.5×10⁵ M⁻¹ sec⁻¹,preferably at least about 5×10⁵ M⁻¹ sec⁻¹, and most preferably at leastabout 7.5×10⁵ M⁻¹ s⁻¹.

[0028] With the advent of methods of molecular biology and recombinantDNA technology, it is now possible to produce antibodies, includingactive fragments thereof, by recombinant means and thereby generate genesequences that code for specific amino acid sequences found in thepolypeptide structure of the antibodies. This has permitted the readyproduction of antibodies having sequences characteristic of neutralizingantibodies from different species and sources.

[0029] Regardless of how they are constructed, antibodies have a similaroverall 3 dimensional structure usually given as L₂H₂ wherein themolecule commonly comprises 2 light (L) amino acid chains and 2 heavy(H) amino acid chains. Both chains have regions capable of interactingwith a structurally complementary antigenic target. The regionsinteracting with the target are referred to as “variable” or “V” regionsand are characterized by differences in amino acid sequence fromantibodies of different antigenic specificity.

[0030] The variable regions of either H or L chains contain the aminoacid sequences capable of specifically binding to antigenic targets.Within these sequences are smaller sequences dubbed “hypervariable”because of their extreme variability between antibodies of differingspecificity. Such hypervariable regions are called “complementaritydetermining regions” or “CDR” regions. These CDR regions account for thebasic specificity of the antibody for a particular antigenic determinantstructure.

[0031] The CDRs represent non-contiguous stretches of amino acids withinthe variable regions but the positional locations of these criticalamino acid sequences within the variable heavy and light chain regionshave been found to have similar locations within the amino acidsequences of the immunoglobulin structure. The variable heavy and lightchains of all antibodies each have 3 CDR regions, each non-contiguouswith the others (termed L1, L2, L3, H1, H2, H3) for the respective lightand heavy chains. The accepted CDR regions have been described by Kabatet al, J Biol. Chem. 252:6609-6616 (1977). The numbering scheme is shownin FIGS. 1-3, where the CDRs are underlined and the numbers follow theKabat scheme.

[0032] In all mammalian species, antibody polypeptides contain constant(i.e., highly conserved) and variable regions comprising both CDRs andso-called “framework regions,” the latter made up of amino acidsequences within the variable region but outside the CDRs.

[0033] Among the properties commonly used to characterize an antibody,or fragment thereof, are the specificity and affinity of the antibody.Specificity refers to the particular ligand, or antigenic structure,that the antibody binds strongly, or most strongly, to. Affinity refersto a quantitative measure of the strength of binding of the antibody toa particular ligand and is given in terms of an “affinity constant.”Such affinity constants may be determined as either association ordissociation constants and represent the ratio of the equilibriumconcentrations of the free ligand and free antibody with respect to theantibody-ligand complex. As used herein, affinity will be given as anassociation constant.

[0034] Such constants are commonly measured by the kinetics ofantigen-antibody complex formation, with the rate constant forassociation to form the complex being denoted as the k_(on) and the rateconstant for dissociation denoted as the k_(off). Measurement of suchconstants is well within the abilities of those in the art. The antibodyand respective antigen combine to form a complex as follows:

Antibody(Ab)+Antigen(Ag)⇄Ab−Ag

[0035] Here, the affinity constant is given as an association constantand thus represents:$K_{a} = \frac{\left\lbrack {{Ab}\text{-}{Ag}} \right\rbrack}{\lbrack{Ab}\rbrack \lbrack{Ag}\rbrack}$

[0036] where K_(a)=the association (or affinity) constant while thebrackets indicate molar concentration of the enclosed species. For agiven set of conditions such as temperature, pressure and ionicstrength, the ratio of the concentration of the complex to the productof the concentrations of the reacting species is constant. So long assaturating conditions are not reached for the antibody or antigen(ligand), a change in concentration of either binding species will alterthe concentration of the complex (Ab−Ag) by an amount dictated by theabove equation (sine K_(a) is constant). Such interaction operatesaccording to a mass-action law.

[0037] In addition, this relationship depends on concentrations and noton absolute amount of the species present so that overall volume is alsorelevant to any measurements of affinity. Thus, if the reaction occursin half the volume, twice as much complex will be formed because eachreactant species (Ab and Ag) is now present at twice the concentrationand so almost four times as much complex will be formed. Conversely,dilution may greatly reduce concentration of the Ab−Ag complex. Ingeneral, the kinetics of antigen-antibody interaction are well known tothose skilled in the art.

[0038] Such antibody-antigen reaction can be described kinetically as adynamic equilibrium where the affinity constant can be measured as aratio of the individual rate constants for formation and dissociation ofthe complex:${Ab} + {{{Ag}\underset{k_{off}}{\overset{k_{on}}{}}{Ab}}\text{-}{Ag}}$

[0039] Thus, the k_(on) value is the rate constant, or specific reactionrate, of the forward, or complex-forming, reaction, measured in units:M⁻¹ sec⁻¹. The k_(off) value is the rate constant, or specific reactionrate, for dissociation of the Ab−Ag complex and is measured in units ofsec⁻¹.

[0040] The values of k_(on) for the antibodies, and active fragmentsthereof, of the present invention were measured using the BlAcoreprotocol and equipment as disclosed in the Examples.

[0041] In accordance with the foregoing, the present invention relatesto high potency neutralizing antibodies, including immunologicallyactive portions, fragments, and/or segments thereof, having a k_(on) ofat least 2.5×10⁵ M⁻¹ s⁻¹, preferably at least about 5×10⁵ M⁻¹ s⁻¹, andmost preferably at least about 7.5×10⁵ M⁻¹ s⁻¹.

[0042] As used herein, the terms “portion,” “segment,” and “fragment,”when used in relation to polypeptides, refer to a continuous sequence ofresidues, such as amino acid residues, which sequence forms a subset ofa larger sequence. For example, if a polypeptide were subjected totreatment with any of the common endopeptidases, such as trypsin,chymotrypsin, pepsin, papain, etc., the oligopeptides resulting fromsuch treatment would represent portions, segments or fragments of thestarting polypeptide. Such proteainases are commonly used to generatefragments of antibodies, such as those described herein, although suchfragments can now more easily be generated by direct cloning orsynthesis of the particular polypeptide desired to be produced.

[0043] The antibodies of the present invention are high potencyantibodies, generally exhibiting high k_(on) values. For purposes of thepresent disclosure, the term “high potency” refers to a potencyreflected by an EC₅₀ (or effective concentration showing at least areduction of 50% in the OD₄₅₀ in the below described microneutralizationassay) of below about 6 nM (nanomolar or 10⁻⁹ molar). The antibodiesaccording to the present invention may be neutralizing (causingdestruction of the target species, such as a virus, and therebydecreasing viral load). An antibody not neutralizing for one use may beneutralizing for a different use.

[0044] The high potency antibodies of the present invention may havespecificity for antigenic determinants found on microbes and are capableof neutralizing said microbes by attaching thereto. In accordance withthe present invention, such microbes are most often viruses, bacteria orfungi, especially organisms that cause respiratory disease and mostpreferably viruses. A specific example, used in the examples herein, isrespiratory syncytial virus (RSV); another example is parainfluenzavirus (PIV).

[0045] The high potency antibodies of the present invention may alsohave specificity for antigens displayed on the surfaces of cancer cells(but will generally not include antibodies, such as vitaxin, that arenon-neutralizing. (See: Wu et al., Proc. Natl. Acad. Sci. 95:6037-6042(1998)) The antibodies of the present invention also include antibodiesfor use in other non-neutralizing reactions.

[0046] The high potency antibodies of the present invention may alsohave specificity for chemical substances such as toxic substances, ortoxins, or for the products of toxins, including, but not limited to,products produced by an organism's metabolism of such toxin(s). Forexample, the high potency antibodies of the present invention may beuseful in nullifying, or otherwise ameliorating, the effects ofaddictive drugs, such as cocaine.

[0047] The high potency antibodies of the present invention may alsohave high affinity for their specific antigen, such as the F antigen ofRSV, and, where such high affinity is exhibited, the affinity constant(K_(a)) of such antibodies is at least about 10⁹ M⁻¹, preferably atleast about 10¹⁰ M⁻¹, and most preferably at least about 10¹¹ M⁻¹.

[0048] The antibodies of the present invention exhibit high potency whenmeasured in, for example, the microneutralization assay described inExample 2. In that assay, high potency is measured by the EC₅₀ value andcommonly have an EC₅₀ of less than about 6.0 nM (nanomolar or 10⁻⁹ M),preferably less than about 3.0 nM, and most preferably less than about1.0 nM. In general, the lower the EC₅₀, the higher the potency, orbiological activity.

[0049] The high potency antibodies of the present invention exhibit suchhigh potency due to their high k_(on) values, which is determined by theamino acid sequences making up the framework (FR) and complementaritydetermining regions (CDRs). These antibodies, or active fragmentsthereof, have high potency complementarity determining regions (CDR)within their amino acid sequences. The high potency neutralizingantibodies of the present invention may comprise at least 2 high potencyCDRs, or 3 high potency CDRs, or even 4 high potency CDRs, or 5 highpotency CDRs, and may even comprise 6 high potency CDRs. Of course, inthe latter case, all 6 CDRs of the antibody, or active fragmentsthereof, are high potency CDRs. In accordance therewith, such highpotency neutralizing antibodies of the present invention have highpotency CDRs that consist of one each of light chain CDRs L1 (CDR L1),L2 (CDR L2), and L3 (CDR L3) and heavy chain CDRs H1 (CDR H1), H2 (CDRH2) and H3 (CDR H3).

[0050] In specific embodiments of such high potency antibodies, saidhigh potency CDRs have amino acid sequences selected from the groupconsisting of SEQ ID NO: 11, 12, 13 and 56 for CDR L1, SEQ ID NO: 14,15, 16, 17, 18, 19, 20, 21, 22, 57 and 58 for CDR L2, SEQ ID NO: 23 forCDR L3, SEQ ID NO: 24 and 25 for CDR H1, SEQ ID NO: 26, 27, 28, 29, 30and 55 for CDR H2, SEQ ID NO: 31, 32, 33 and 34 for CDR H3.

[0051] In preferred embodiments, the high potency neutralizingantibodies of the present invention comprise variable heavy and lightchains with amino acid sequences selected from the group consisting ofSEQ ID NO: 35 and 36.

[0052] The present invention further relates to a process for producinga high potency antibody comprising:

[0053] (a) producing a recombinant antibody, including immunologicallyactive fragments thereof, comprising heavy and light chain constantregions derived from a mammalian antibody and heavy and light chainvariable regions containing one or more framework and/or complementaritydetermining regions (CDRs) having preselected amino acid sequences;

[0054] (b) screening said recombinant antibodies for high k_(on) whensaid antibody reacts in vitro with a selected antigen; and

[0055] (c) selecting antibodies with said high k_(on).

[0056] The antibodies produced according to the present invention willcommonly have high affinity constants and high k_(on) values, the latteryielding high biological activity, or potency. In specific embodiments,the high potency antibodies produced according to the present inventioncommonly have a k_(on) of at least about 2.5×10⁵ M⁻¹ s⁻¹, preferably atleast about 5×10⁵ M⁻¹ s⁻¹, and most preferably at least about 7.5×10⁵M⁻¹ s⁻¹.

[0057] In one embodiment, the processes of the invention produce a highpotency antibody wherein the preselected amino acid sequences producinga high k_(on) (and resulting high potency) are present in either bothframework region and at least two or three CDR regions, perhaps all sixCDR regions, of the antibody or are restricted to just CDR regions.

[0058] In another embodiment, the preselected amino acid sequencesproducing a high k_(on) are present in either both framework region andat least three CDR regions of the antibody or are restricted to just CDRregions.

[0059] In an additional embodiment, the preselected amino acid sequencesproducing a high k_(on) are present in either both framework region andat least four CDR regions of the antibody or are restricted to just CDRregions.

[0060] In addition, the antibodies produced according to the presentinvention may be complete tetrameric antibodies, having the H₂L₂structure, or may be fragments of such antibody structures, includingsingle chain antibodies or fragments such as Fab or F(ab)₂′ fragments.

[0061] In accordance with the present invention, the antigens for whichthe antibodies are specific are often, but not always, antigensexpressed by viruses, such as respiratory syncytial virus (RSV) orparainfluenza virus (PIV).

[0062] The present invention also relates to a process for producing ahigh potency antibody comprising producing a recombinant antibodycomprising heavy and light chain constant region derived from amammalian antibody and heavy and light chain variable regions containingframework and/or complementarity determining regions (CDR) wherein atleast one CDR is a high k_(on) (or high potency) CDR having an aminoacid sequence not found in nature and wherein the presence of said CDRresults in a high k_(on) .

[0063] In specific embodiments, the processes of the present inventionproduce high potency recombinant antibodies wherein the recombinant highk_(on) antibody comprises at least two high k_(on) CDRs, possibly threehigh k_(on), CDRs, and even four high k_(on) CDRs, and as many as fiveor six high k_(on) CDRs. The presence of such CDR sequences result inthe antibody, or fragment, exhibiting a high k_(on) and thereby a highpotency.

[0064] In further embodiments of the methods of the invention, theaforementioned high association constant of the antibodies produced bythe methods of the invention are at least about 2.5×10⁵ M⁻¹ s⁻¹,preferably at least about 5×10⁵ M⁻¹ s⁻¹, and most preferably at leastabout 7.5×10⁵ M⁻¹ s⁻¹.

[0065] The present invention further relates to a process for producinga high potency antibody comprising:

[0066] (a) producing a recombinant antibody, including immunologicallyactive fragments thereof, comprising heavy and light chain constantregions derived from a mammalian antibody and heavy and light chainvariable regions containing one or more framework and/or complementaritydetermining regions (CDRs) having preselected amino acid sequences;

[0067] (b) screening said recombinant antibodies for both high affinityand high k_(on) when said antibody reacts in vitro with a selectedantigen; and

[0068] (c) selecting antibodies with both high affinity and high k_(on).

[0069] In preferred embodiments of the present invention, the processesdisclosed herein produce high potency antibodies having both highaffinity and high k_(on) wherein the affinity constant is at least 10⁹M⁻¹ and k_(on) is at least 2.5×10⁵ M⁻¹ s⁻¹, especially where saidaffinityis at least 10¹⁰ M⁻and said k_(on) is at least 2.5×10⁵ M⁻¹ S⁻¹,most especially where said affinity constant is at least 10¹¹ M⁻¹ andsaid kn is at least 2.5×10⁵ M⁻¹ s⁻¹, with most preferred embodimentshaving very high affinity and k_(on) , especially where said affinity isat least 10⁹ M¹ and said k_(on) is at least 5×10⁵ M⁻¹ s⁻¹, and mostespecially where the affinity constant is at least 10¹⁰ M⁻¹ and k_(on)is at least 2.5×10⁵ M⁻¹ s⁻¹, a most especially preferred embodimentbeing one wherein the processes of the invention produce a high potencyantibody wherein the affinity constant is at least 10¹¹ M⁻¹ and thek_(on) is at least 7.5×10⁵ M⁻¹ s⁻¹. It is to be understood that, wherehigh affinity is also sought, any combination of the above mentionedaffinity (K_(a)) and kinetic association (k_(on) ) values are within thepresent invention.

[0070] These embodiments of the present invention also include processeswherein the preselected amino acid sequence producing a high k_(on) ispresent in either both framework region and CDR regions, or just CDRregions, and wherein such sequences, selected from SEQ ID NO: 11 to 34and 55 to 58, are present in 1, 2, 3, 4, 5, or all 6, CDR regions,wherein the individual CDR sequence is selected from the individualsequences as disclosed herein. Methods of doing this are well within theskill of those in the art and will not be discussed further herein.

[0071] The methods of the present invention are not limited to merelyproducing novel high affinity antibodies that are specific for aparticular antigen and which have been produced without regard toalready existing immunogenic molecules and structures. Thus, the methodsdisclosed herein provide a means for selected modifications to thestructures of known antibody molecules, thereby producing increases inthe k_(on) of such antibodies and concomitant increased biologicalactivity. This is accomplished by selective incorporation of the highpotency CDR sequences disclosed herein.

[0072] In separate embodiments of the present invention, the antibodywhose potency is to be increased will have an initial and/or finalaffinity constant of at least 10⁹ M⁻¹, preferably at least about 10¹⁰M⁻¹, and most preferably at least about 10¹¹ M⁻¹.

[0073] In accordance with the present invention, the antibodies producedaccording to the methods of the invention will have higher k_(on)constants after amino acid changes to produce high potency sequences ofthe invention and as a result of said amino acid changes, especiallywhere the k_(no) value following said amino acid changes is at least2.5×10⁵ M⁻¹ sec⁻¹, especially at least about 5×10⁵ M⁻¹ s⁻¹, and mostespecially at least about 7.5×10⁵ M⁻¹ s⁻¹ (regardless of the particularaffinity constant) (K_(a)).

[0074] In applying the methods of the present invention it is to beunderstood that the aforementioned changes in amino acid sequence usedto increase the potency of an antibody, or active fragments thereof, orthe use of selected amino acid sequences to produce high potencyantibodies, or active high potency fragments thereof, achieve said highpotency, or increased potency, through the production of high k_(on)values. Because the affinity constant is a numerical ratio of k_(on) tok_(off), an increased k_(on) may result in increased affinity if thek_(off) is not changed by the same factor. Thus, high potencies of theantibodies produced according to the present methods are a function ofthe value of k_(on) and not the value of K_(a) (the affinity constant).For example, the use of selected amino acid sequences in the CDRs of anantibody molecule may result in a sizeable increase in both association(k_(on)) and dissociation (k_(off)) rate constants and, if both areincreased by the same factor, the result is a high, or higher, potency(due to the higher k_(on)) but with no resulting increase in K_(a)(because the ratio of the k_(on) to k_(off) is the same). Conversely,where use of such preselected amino acid sequences within the CDRs of ahigh potency antibody results in a decreased k_(off) and no increasedk_(on), the result is an antibody, or active fragment thereof, withhigher affinity but with little or no increase in potency. Thus, it hasbeen found that there is little or no change in potency where thek_(off) value alone changes (because K_(a) is the ratio of k_(on) tok_(off)) but k_(on) remains constant despite a numerical change inK_(a).

[0075] In accordance with the present invention, several convenientmethods are available for measurement of the potency of antibodies, oractive fragments thereof, such as Fab fragments. One such method usesthe cotton rat model, details of which are disclosed in the examplesprovided below. Another is the microneutralization assay (see Example2).

[0076] Also in accordance with the present invention, there is provideda process for preventing or treating a disease comprising administeringto a patient at risk of such disease, or afflicted with such disease, atherapeutically (or prophylactically) effective amount of a high potencyantibody, or active fragment thereof, having a polypeptide sequence asdisclosed herein or produced according to the methods disclosed herein.In a preferred embodiment, the disease is caused by a virus, especiallyone selected from the group respiratory syncytial virus andparainfluenza virus.

[0077] The highly potent neutralizing antibodies of the presentinvention are achieved through generating appropriate antibody genesequences, i.e., amino acid sequences, by arranging the appropriatenucleotide sequences and expressing these in a suitable cell line. Anydesired nucleotide sequences can be produced using the method of codonbased mutagenesis, as described, for example, in U.S. Pat. Nos.5,264,563 and 5,523,388 (the disclosures of which are herebyincorporated by reference in their entirety). Such procedures permit theproduction of any and all frequencies of amino acid residues at anydesired codon positions within an oligonucleotide. This can includecompletely random substitutions of any of the 20 amino acids at andesired position or in any specific subset of these. Alternatively, thisprocess can be carried out so as to achieve a particular amino acid adesired location within an amino acid chain, such as the novel CDRsequences according to the invention. In sum, the appropriate nucleotidesequence to express any amino acid sequence desired can be readilyachieved and using such procedures the novel CDR sequences of thepresent invention can be reproduced. This results in the ability tosynthesize polypeptides, such as antibodies, with any desired amino acidsequences. For example, it is now possible to determine the amino acidsequences of any desired domains of an antibody of choice and,optionally, to prepare homologous chains with one or more amino acidsreplaced by other desired amino acids, so as to give a range ofsubstituted analogs.

[0078] In applying such methods, it is to be appreciated that due to thedegeneracy of the genetic code, such methods as random oligonucleotidesynthesis and partial degenerate oligonucleotide synthesis willincorporate redundancies for codons specifying a particular amino acidresidue at a particular position, although such methods can be used toprovide a master set of all possible amino acid sequences and screenthese for optimal function as antibody structures or for other purposes.Such methods are described in Cwirla et al, Proc. Natl. Acad. Sci.87:6378-6382 (1990) and Devlin et al., Science 249:404-406 (1990).Alternatively, such antibody sequences can be synthesized chemically orgenerated in other ways well known to those skilled in the art.

[0079] In accordance with the invention disclosed herein, enhancedantibody variants can be generated by combining in a single polypeptidestructure one, two or more novel CDR sequences as disclosed herein (see,for example, SEQ ID NO: 11-34), each shown to independently result inenhanced potency or biological activity. In this manner, several novelamino acids sequences can be combined into one antibody, in the same ordifferent CDRs, to produce antibodies with desirable levels ofbiological activity. Such desirable levels will often result fromproducing antibodies whose k_(on) values are at least about 2.5×10⁵ M⁻¹sec⁻¹. By way of non-limiting example, 3 such novel CDR sequences may beemployed and the resulting antibodies screened for potency, orbiological activity, using either the cotton rat protocol or themicroneutralization protocol described herein, where the said antibodydemonstrates high affinity for a particular antigenic structure, such asthe F antigen of RSV. The overall result would thus be an iterativeprocess of combining various single amino acid substitutions andscreening the resulting antibodies for antigenic affinity and potency ina step by step manner, thereby insuring that potency is increasedwithout sacrifice of a desirably high, or at least minimum value for,affinity.

[0080] Using the novel sequences and methods of the present invention,such an approach would avoid the time and expense of generating andscreening all possible permutations and combinations of antibodystructure in an effort to find the antibody with the maximum efficacy.Conversely, complete randomization of a single 10 amino acid residue CDRwould generate over 10 trillion variants, a number virtually impossibleto screen.

[0081] This iterative method can be used to generate double and tripleamino acid replacements in a stepwise process so as to narrow the searchfor antibodies having higher affinity.

[0082] Conversely, it must be appreciated that not all locations withinthe sequences of the different antibody domains may be equal.Substitutions of any kind in a particular location may be helpful ordetrimental. In addition, substitutions of certain kinds of amino acidsat certain locations may likewise be a plus or a minus regardingaffinity. For example, it may not be necessary to try all possiblehydrophobic amino acids at a given position. It may be that anyhydrophobic amino acid will do as well. Conversely, an acidic or basicamino acid at a given location may provide large swings in measuredaffinity. It is therefore necessary also to learn the “rules” of makingsuch substitutions but the determination of such “rules” does notrequire the study of all possible combinations and substitutions—trendsmay become apparent after examining fewer than the maximum number ofsubstitutions.

[0083] In accordance with the present invention, such rules determinethe amino acid changes that must be made in the CDR regions ofantibodies, or the amino acid sequences that must be prepared in whollynovel and synthetic antibody polypeptides, so as to achieve highaffinities. However, it has now been discovered that, while highaffinity is often a property of antibodies useful in therapeuticapplications, such antibodies do not always have a sufficient potency toafford practical utility in such uses.

[0084] As already described, affinity is measured by the ratio of thek_(on) and k_(off) constants. For example, a k_(on) of 10⁵ M⁻¹ sec⁻¹ anda k_(off) of 10⁵ sec⁻¹ would combine to give an affinity constant of10¹⁰ M⁻¹ (see values in Table 3). However, antibodies showing such highaffinity may still lack the potency required to make them usefultherapeutic agents. In accordance with the present invention, antibodypotency is dependent on the value of the k_(on) rate for the antibodybinding reaction. Thus, an antibody, regardless of affinity for therespective antigen, will exhibit an increase in potency (such asneutralizing ability) where said antibody has a higher k_(on) value,regardless of K_(a) or k_(off).

[0085] In accordance with the methods of the present invention,increased potency of an existing antibody, regardless of its antigenaffinity, is achieved through selective changes to one or more of theamino acids present in one or more of the CDR regions of said antibodywhereby said amino acid changes have the effect of producing an increasein the k_(on) for said antibody, preferably with an increase in antibodyaffinity. Higher potency can be achieved with a higher k_(on) value evenif the affinity remains the same or is reduced somewhat. Such anantibody is most advantageously produced by synthesis of the requiredpolypeptide chains via synthesis in suitably engineered cells havingincorporated therein the appropriate nucleotide sequences coding for therequired polypeptide chains containing the altered CDR segments. Also inaccordance with the methods of the present invention, a novel antibodyhaving a desirable level of potency, or biological activity, can beprepared de novo by incorporation of selected amino acids at selectedlocations within the CDR regions of said antibody polypeptide chainsusing genetically engineered cells as described herein or wholly throughchemical synthesis of the required polypeptide chains with subsequentformation of the necessary disulfide bonds.

[0086] In this regard, it should be kept clearly in mind that theantibodies produced according to the methods of the present inventionmay be antibodies possessing tetrameric, dimeric or monomericstructures. Thus, the term “antibody” as used herein includes wholetetrameric antibody molecules, as are commonly found in nature, as wellas portions and fragments thereof, including L₂H₂, LH, Fab, F(ab′)₂, andother fragments, the only requirement of such structures being that theyretain biological activity as measured by the assays and protocolsdescribed herein.

[0087] In accordance with the foregoing, the antibodies of the presentinvention are high affinity monoclonal antibodies. Such antibodies,however, are monoclonal only in the sense that they may be derived froma clone of a single cell type. However, this is not meant to limit themto a particular origin. Such antibodies may readily be produced in cellsthat commonly do not produce antibodies, such as CHO or COS cells. Inaddition, such antibodies may be produced in other types of cells,especially mammalian and even plant cells, by genetically engineeringsuch cells to express and assemble the polypeptide light and heavychains forming the antibody product. In addition, such chains can bechemically synthesized but, since they would be specific for a givenantigenic determinant, would still constitute “monoclonal” antibodieswithin the spirit in which that term is used. Thus, as used herein, theterm monoclonal antibody is intended to denote more the specificity andpurity of the antibody molecules produced by the methods disclosedherein rather than the mere mechanism used for production of saidantibodies.

[0088] Also as used herein, the term potency is intended to describe thedependency of the effect of the antibody, when utilized for its intendedpurpose, on the concentration of such antibody. Thus, potency meansbiological activity with respect to a given antigen. By way ofnon-limiting example, the potency, or biological activity, or biologicaleffect, is measured for an anti-RSV antibody, by either the cotton ratprocedure or the microneutralization procedure, as described in theMethods section. Conversely, the affinity of an antibody for the antigenis simply a mathematical measure of the ratio of k_(on) to k_(off).

[0089] In addition, the affinities (K_(a)) of the antibodies producedaccording to the methods of the present invention will typically be inthe range of 10¹⁰ M⁻¹. This range may, for example, be within 10-fold,higher or lower, of 10¹⁰ M⁻¹ or be more than 10-fold greater than 10¹⁰M⁻¹ or may even be numerically equal to 10¹⁰ M⁻¹. The affinity of theantibody for antigen is proportional to the value of this constant(i.e., the higher the constant, the greater the affinity due to greaterconcentration of the complex—see the equation for the affinityconstant). Such a constant is measured by standard kinetic methodologyfor antibody reactions (as described in Example 1).

[0090] In one embodiment, the antibodies produced according to themethods of the present invention (other than where the term “antibody”means an active portion, fragment or segment, all of which, for purposesof the present disclosure, are considered to be included within themeaning of the term antibody) will commonly comprise a mammalian,preferably a human, constant region and a variable region, said variableregion comprising heavy and light chain framework regions and heavy andlight chain CDRs, wherein the heavy and light chain framework regionshave sequences characteristic of a mammalian antibody, preferably ahuman antibody, and wherein the CDR sequences are similar to those of anantibody of some species other than a human, preferably a mouse. Wherethe framework amino acid sequences are characteristic of those of anon-human, the latter is preferably a mouse.

[0091] In another embodiment, the antibody is a human antibody whereinthe antibody has a k_(on) value as herein described to provide forimproved potency.

[0092] In addition, antibodies produced according to the presentinvention will commonly bind the same epitope as prior to applying themethods disclosed herein to increase the k_(on) value. Thus, afterapplying the methods of the present invention, the antibody will haveCDR sequences similar, but not identical, to the CDR sequences prior toapplication of the methods disclosed herein in that at least one of theCDRs of said antibody will contain a high potency amino acid sequence,such as one selected from SEQ ID NO: 11-34 if the antibody is to be usedto neutralize a virus such as RSV.

[0093] In keeping with the foregoing, and in order to better describethe sequences disclosed according to the invention with respect to ahumanized antibody against RSV, a basic or starting sequence of lightand heavy chain variable regions of an antibody, or fragment thereof,whose potency is to be increased, are shown in FIG. 1A (light chainvariable region—SEQ ID NO: 1) and FIG. 1B (heavy chain variableregion—SEQ ID NO: 2) or an Fab fragment of such an antibody (forexample, the sequences of FIG. 2a (light chain variable region—SEQ IDNO: 3) and FIG. 2B (heavy chain variable region—SEQ ID NO: 4). Also inaccordance with the invention, specific amino acids different from thoseof these starting sequences were generated by recombinant methodsstarting with prepared nucleotide sequences designed to generate saidamino acid sequences when expressed in recombinant cells. The productsof said cells are the monoclonal antibodies of the present invention.Alternatively, such antibodies can be produced without the use of anengineered or recombinant cell by synthetic means well known in the art.

[0094] In one embodiment of the present invention, potency is increasedusing a neutralizing antibody against respiratory syncytial virus (RSV)having an affinity constant of at least 10⁹ M⁻¹, and preferably at least10¹⁰ M⁻¹ (for the F antigen thereof) by increasing the k_(on) value toat least 2.5×10⁵ M⁻¹ sec⁻¹. The amino acids present in the CDRs of suchan Fab fragment are shown in Table 3 (for example, clone 5).

[0095] In general, the approach used to determine affinity and kineticconstants of antibodies before and after application of the methods ofthe invention to increase the k_(on) value, was to generate nucleotidesequences for the genes expressing the desired antibody chains (inaccordance with the present invention) and insert these into vectorsthat were then used to transform COS-1 cells by standard protocols. Thecells were grown in wells and the supernatant sampled and measured forantigen binding using standard ELISA techniques. These polynucleotideswere designed so as to provide one or more amino acid replacements inthe CDRs that could then be screened for increased k_(on) values, withbeneficial replacements (those yielding increased k_(on) values) beingselectively combined for increased affinity. These are then subsequentlyscreened for binding affinity for the respective antigen, such as the Fantigen of RSV versus the basic or reference structure, therebydetermining that no serious change in affinity resulted from theincrease in k_(on) values.

[0096] In specific embodiments, the present invention relates to anisolated antibody comprising an affinity constant of at least 10⁹ M⁻¹,preferably at least 10¹⁰ M⁻¹ and most preferably at least 10¹¹ M⁻¹ andwherein the k_(on) is at least about 2.5×10⁵ M⁻¹ sec⁻¹, preferably atleast about 5×10⁵ M⁻¹ sec⁻¹, and most preferably at least 7.5×10⁵ M⁻¹sec⁻¹ (including all combinations thereof).

[0097] Also in accordance with the present invention, such isolatedantibody may be any kind of antibody already known or newly synthesizedand novel. Thus, antibodies produced according to the methods of thepresent invention will include an antibody selected from the groupconsisting of a naturally occurring mammalian antibody, naturallyoccurring human antibodies, naturally occurring mouse antibodies, singlechain antibodies, chimeric antibodies (having constant regions of anantibody of one species and variable regions of an antibody of adifferent species), CDR-grafted antibodies (having the CDR regions of anantibody of one species and the constant and, possibly, frameworkregions of an antibody of a different species), humanized antibodies (inwhich selected amino acids, of either the variable framework and/or CDRregions, have been altered so as to be similar to a human antibodydespite such sequences being largely derived from a different species,such as a mouse), preferably humanized mouse antibodies, alteredmammalian, preferably mouse, most preferably human, antibodies (whereinselected amino acids of an existing antibody have been altered at somepoint in the polypeptide chain, commonly through the techniques ofgenetic engineering, to afford antibody structures similar to theantibody structures on which they are based), and wholly synthetic novelantibodies, the latter not previously existing in nature.

[0098] The present invention also relates to methods of increasing thepotency of one of the aforementioned types of antibodies (as previouslydescribed) comprising selectively changing the amino acids within thevariable regions of the antibody so as to increase the measured k_(on)value of said antibody with respect to a particular antigen. Of course,the kn value may be different for the same antibody following the sameamino acid changes where the reaction is measured using a differentantigen or antigenic determinant. However, in such cases, affinities arealso likely to change as the identity of the antigenic determinantchanges.

[0099] Also in accordance with the methods of the present invention theamino acid changes introduced into the sequences of the polypeptides ofsuch antibodies are preferably restricted to the CDR portions of thevariable regions of the antibodies although these could involve changesto the framework regions as well.

[0100] Although the most advantageous CDR sequences are commonlyidentified by screening modified clones of antibodies whose potency isto be increased by the methods disclosed herein, once such high potencyclones have been identified the resulting antibody is mostadvantageously produced thereafter through synthesis of the appropriateheavy and light polypeptide chains within suitable animal or plant cellsfollowing introduction into such cells of suitable vectors containingthe appropriate DNA sequences corresponding to the desired amino acidsequences, taking advantage of the genetic code to design the requirednucleotide sequences. As a consequence of this approach, wholly novelantibodies with high potency can be produced at the outset using theamino acid sequence identities suggested by the methods of the presentinvention without the need to select already existing antibody sequencesfor modification. Thus, the methods disclosed herein facilitate theproduction of high potency antibodies of a completely novel structure inthat their CDR sequences are high potency CDRs as determined by themethods disclosed herein so as to deliberately increase the k_(on)values of such antibodies and without destroying the specificity andaffinity of such antibody for the intended antigenic target.

[0101] In one embodiment of the methods of the present invention, analready existing antibody is modified to increase the potency thereof byincreasing the k_(on) value. In a preferred embodiment, the antibody isone with high affinities, e.g., at least about 10⁹ M⁻¹ or 10¹⁰ M⁻¹. Theantibody is synthesized, using clones or genetically engineered animalor plant cells, so as to introduce amino acid changes into the heavyand/or light polypeptide chains of said antibody, preferably where saidantibody changes are introduced into the complementarity determiningregions (CDRs) of said polypeptide chains, to increase the k_(on) valuefor binding of said antibody to a particular antigen with concomitantincrease in the potency of the antibody. Thus, the methods of thepresent invention are advantageously utilized to produce an antibodymolecule wherein the k_(on) value of said antibody following the aminoacid changes to its sequence, preferably the variable regions of saidsequence, most preferably the CDR portions, is higher than the k_(on)value exhibited by said antibody prior to said amino acid changes whenthe k_(on) values are measured with respect to the same antigen.

[0102] In general, where the methods of the present invention areapplied to known antibodies, the k_(on) of said antibodies will beincreased by at least 2-fold, preferably at least 5-fold, and mostpreferably at least 10-fold. More specifically, the k_(on) value of saidantibody is increased to at least about 2.5×10⁵ M⁻¹ sec⁻¹, preferablyincreased to at least 5×10⁵ M⁻¹ sec⁻¹, most preferably at least 7.5×10⁵M⁻¹ sec⁻¹.

[0103] Because the methods disclosed herein are equally effective fordesigning novel recombinant high potency antibodies previously unknown,the present invention also relates to a method of producing an antibodyhaving a k_(on) value of at least 2.5×10⁵ M⁻¹ sec⁻¹, comprisingpreparing an antibody whose polypeptide sequences contain selected aminoacids at selected locations, especially within the CDR sequences, andthen screening said antibodies for those having a k_(on) value of atleast 2.5×10⁵ M⁻¹ sec⁻¹, or a k_(on) value of at least 5×10⁵ M⁻¹ sec⁻¹or even 7.5×10⁵ M⁻¹ sec⁻¹. Such antibodies will result from the presenceof one or more of the high potency CDRs as disclosed herein. Suchantibodies are readily screened for high k_(on) values.

[0104] The methods of the present invention can be utilized for theproduction of antibodies with high potency, or antibodies of increasedpotency, having affinity for any desired antigen, although such antigenis preferably an antigen characteristic of a microorganism, such as abacterium, virus, or fungus, preferably a virus (for example,respiratory syncytial virus (RSV)).

[0105] In another embodiment, the present invention relates to a methodof preventing or treating a disease comprising administering to apatient at risk of such disease, or afflicted with such disease, of atherapeutically active amount of an antibody prepared by the methodsdisclosed herein. Thus, such antibody may be a completely novel antibodyor a known and clinically useful antibody whose potency has beenincreased by application of the methods of the present invention. Thedisease prevented or treated by antibodies prepared by the methodsdisclosed herein may commonly be diseases caused by microorganisms, suchas bacteria and viruses, preferably viruses and most preferably RSV.

[0106] The antibodies thus disclosed will also commonly have frameworkregions derived from a human antibody but, where not so derived,preferably from a mouse.

[0107] In generating the clones, the basic or reference antibody (heavyand light chain variable regions (CDRs plus Framework) shown in FIGS. 1and 2) was used as the “template” for generating the novel CDR sequencesof the antibodies of the present invention, the latter imparting higherk_(on) values. Standard approaches to characterizing and synthesizingthe six CDR libraries of single mutations were used (see Wu et al, Proc.Natl. Acad. Sci. 95:6037-6042 (1998), the disclosure of which is herebyincorporated by reference in its entirety). The target CDR was firstdeleted for each of the libraries prior to annealing the nucleotides.For synthesis of the libraries, the CDRs of a reference antibody (seeFIG. 2) were defined as in Table 1. Codon based mutagenesis foroligonucleotide synthesis to yield the CDR sequences of the inventionwas employed (as described above).

[0108] Libraries were initially screened by capture lift to identify thehighest affinity variants. Subsequently, these clones were furthercharacterized using capture ELISA and by titration on immobilizedantigen. Following such screening, the antibodies are then screened fortheir respective k_(on) values, the positive effects of which are thenmeasured by determination of potency. FIGS. 4 and 5 show additionaldetails on preparation and screening procedures used herein.

[0109] Table 1. Basic CDR sequences as provided in FIG. 2. TABLE 1 BasicCDR sequences as provided in FIG. 2. CDR Residues of FIG. 2 Sequence SEQID NO. L1 24-33 SASSSVGYMH 5 L2 49-55 DTSKLAS 6 L3 88-96 FQGSGYPFT 7 H131-37 TSGMSVG 8 H2 52-67 DIWWDDKKDYNPSLKS 9 H3 100-109 SMITNWYFDV 10 

[0110] In accordance with the present invention, DNA from the highestk_(on) variants was sequenced to determine the nature of the beneficialor high potency replacements. After screening, antibodies are thenprepared with the high-k_(on) amino acid replacements, either singly orin various combinations, so as to maximize the effects of suchsubstitutions and thereby produce high affinity antibodies alsoexhibiting high potency.

[0111] As a general rule, the most beneficial of high k_(on) CDRs werefound to result from amino acid replacements in up to 6 CDRs. Thus, thehigh potency (i.e., high k_(on) ) neutralizing antibodies disclosedherein contain amino acid sequences differing from that of the base orreference antibody (for example, as shown in FIGS. 1 and 2) only incomplementarity determining regions L1 (or CDRL1), L2 (or CDRL2), L3 (orCDRL3), H1 (or CDRH1) and H3 (or CDRH3). TABLE 2 Sequences of CDRstending to induce high potency in antibodies High Potency Clone CDR CDRSequence SEQ ID NO.  1 L1 SASSSVGYMH  5 L2 X DT F KL T S 14 L3 FQGSGYPFT 7 H1 X T A GMSVG 24 H2 DIWWDDKKDYNPSLKS  9 H3 X D MITN F YFDV 31  2 L1SASSSVGYMH  5 L2 X DT F KLAS 15 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2DIWWDDKKDYNPSLKS  9 H3 X D MI F NWYFDV 32  3 L1 SASSSVGYMH  5 L2 X DT YK QT S 16 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2 DIWWDDKKDYNPSLKS  9 H3 XD MI F NWYFDV 32  4 L1 SASSSVGYMH  5 L2 X DT RY L S S 17 L3 FQGSGYPFT  7H1 X T A GMSVG 24 H2 DIWWDDKKDYNPSLKS  9 H3 X D MI F NWYFDV 32  5 L1SASSSVGYMH  5 L2 X DT F KLAS 15 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2DIWWDDKKDYNPSLKS  9 H3 X D MITNFYFDV 31  6 L1 SASSSVGYMH  5 L2 X DT FKLAS 15 L3 X FQGS F YPFT 23 H1 X T A GMSVG 24 H2 DIWWDDKKDYNPSLKS  9 H3X SMITN F YFDV 33  7 L1 X SASS R VGYMH 11 L2 X DT F KLAS 15 L3 FQGSGYPFT 7 H1 X T A GMSVG 24 H2 DIWWDDKKDYNPSLKS  9 H3 X D MITN F YFDV 31  8 L1SASSSVGYMH  5 L2 X DT FR LAS 16 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2DIWWDDKKDYNPSLKS  9 H3 X D MITN F YFDV 31  9 L1 X S L SS R VGYMH 12 L2 XDT FY L S S 17 L3 FQGSGYPFT  7 H1 X T P GMSVG 25 H2 X DIWWDDKK H YNPSLKD 26 H3 X D MIFN F YFDV 34 10 L1 X S L SS R VGYMH 12 L2 X DT RG L P S 18L3 FQGSGYPFT  7 H1 X T P GMSVG 25 H2 X DIWWD G KK H YNPSLK D 27 H3 X DMIFN F YFDV 34 11 L1 X S P SS R VGYMH 13 L2 X DT MR LAS 19 L3 FQGSGYPFT 7 H1 X T P GMSVG 25 H2 X DIWWD G KK H YNPSLK D 27 H3 X D MIFN F YFDV 3412 L1 X S L SS R VGYMH 12 L2 X DT F KL S S 20 L3 FQGSGYPFT  7 H1 X T AGMSVG 24 H2 X DIWWD G KK H YNPSLK D 27 H3 X D MIFN F YFDV 34 13 L1 XSASS R VGYMH 11 L2 X DT F KL S S 10 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2X DIWWD G KKDYNPSLK D 28 H3 X D MI F N F YFDV 34 14 L1 X S P SS R VGYMH13 L2 X DT YRHS S 21 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2 X DIWWDDKK HYNPSLK D 29 H3 X D MI F NWYFDV 32 15 L1 X S L SS R VGYMH 12 L2 X DT MYQSS 22 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2 X DIWWD G KK S YNPSLK D 30 H3X D MI F N F YFDV 34 16 L1 KCQLSVGYMH 59 L2 DTSKLAS  6 L3 FQGSGYPFT  7H1 TSGMSVG  8 H2 DIWWDDKKDYNPSLKS  9 H3 SMITNWYFDV 10 17 L1 SASSSVGYMH 5 L2 DT F KLAS 15 L3 FQGS F YPFT 23 H1 T A GMSVG 24 H2 DIWWDDKKDYNPSLKS 9 H3 SMITN F YFDV 33 18 L1 X LPSSRVGYMH 56 L2 X DTMYQSS 22 L3 FQGSGYPFT 7 H1 X T A GMSVG 24 H2 X DIWWDGKKSYNPSLKS 55 H3 X DMIFN F YFDV 31 19 L1X SASSRVGYMH 11 L2 X DT FF LDS 57 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2 XDIWWDDKKHYNPSLKD 26 H3 X DMIFN F YFDV 31 20 L1 X SPSSRVGYMH 13 L2 X DTRYQS S 58 L3 FQGSGYPFT  7 H1 X T A GMSVG 24 H2 X DIWWDDKKSYNPSLKD 55 H3X DMIFNWYFDV 32

[0112] Thus, for the amino acid sequences of FIG. 3, selected aminoacids of the sequence of FIG. 2 were replaced as a means of increasingthe potency of the antibody with heavy and light chain sequences shownin FIG. 2.

[0113] Selected high k_(on) antibodies (and active fragments thereof)resulting from the methods disclosed herein are shown in Table 2 (all ofwhich have the framework sequences of FIG. 2) where the reference cloneis the clone with heavy and light chain variable region sequences shownin FIG. 2 (SEQ ID NO: 3 and 4 for the light and heavy sequences,respectively).

[0114] Table 2 indicates the amino acid sequences (all sequences instandard amino acid one letter code) of the high k_(on) CDRs employed inthe high potency antibodies prepared according to the methods disclosedherein. In table 2, the locations of key amino acid substitutions madein the corresponding CDRs of table 1 (i.e., locations at which CDRsdiffer in amino acids) are indicated in bold face and underlined.

[0115] In accordance with the invention, by combining such amino acidsubstitutions so that more than one occurred in the same antibodymolecule, it was possible to greatly increase the potency of theantibodies disclosed herein.

[0116] In general, there is a correlation between k_(on) and potency ofthe antibody, with all of the higher k_(on) variants having more thanone beneficial or high k_(on) CDR, including having all six CDRssubstituted.

[0117] In one embodiment, an antibody prepared so as to have increasedk_(on) is an RSV-neutralizing antibody, with an affinity of at least 10⁹M⁻¹ and preferably at least 10¹⁰ M⁻¹, that is also a humanized antibodythat includes a human constant region and a framework for the heavy andlight chains wherein at least a portion of the framework is derived froma human antibody (or from a consensus sequence of a human antibodyframework).

[0118] In another embodiment, all of the framework is derived from ahuman antibody (or a human consensus sequence).

[0119] In another embodiment, an antibody produced according to thepresent invention, with an affinity of at least 10⁹ M⁻¹ and preferablyat least 10¹⁰ M⁻¹, is a grafted antibody having a human constant region,one or more CDRs that are derived from a non-human antibody in which atleast one of the amino acids in at least one of said CDRs is changed andin which all or a portion of the framework is derived from a humanantibody (or a consensus sequence of a human antibody framework).

[0120] So long as the desired CDR sequences, and the constant andframework sequence are known, genes with the desired sequences can beassembled and, using a variety of vectors, inserted into appropriatecells for expression of the functional tetrameric antibody molecules.Coupling this with the methodology already described, permits theassembly of single mutation libraries wherein the antibodies possess thesame sequences as corresponding grafted antibodies and, therefore, thesame structure and binding affinities.

[0121] The combinations of CDR sequences disclosed in Table 2 can bepresent in whole tetrameric antibody molecules or in active fragments,such as Fab fragment. The potency data for clones 1 through 15 shown inTable 3 are for Fab fragments while the data for clones 16 and 17 ofTable 3 are for whole antibody molecules (clone 16 is MEDI-493 withsequence disclosed in Johnson et al (1997)).

[0122] Whole antibody molecules according to the present inventioninclude antibody molecules having heavy chain sequences (variable plusconstant region) selected from the group consisting of SEQ ID NO: 37,39, 41, 43, 45, 47, 49, 51 and 53 and with light chain sequences(variable plus constant region) selected from the group consisting ofSEQ ID NO: 38, 40, 42, 44, 46, 48, 50, 52, and 54.

[0123] The relatively high k_(on) antibodies of the invention can bepresent in a relatively pure or isolated form as well as in asupernatant drawn from cells grown in wells or on plates. The antibodiesof the invention can thus also be present in the form of a compositioncomprising the antibody of the invention and wherein said antibody issuspended in a pharmacologically acceptable diluent or excipient. Theantibodies of the invention may be present in such a composition at aconcentration, or in an amount, sufficient to be of therapeutic orpharmacological value in treating or preventing diseases, (for example,preventing RSV, including the higher incidence of asthma and wheezingthat often occur following such infections). Said antibodies may also bepresent in a composition in a more dilute form.

[0124] Consequently, the invention is also directed to providing amethod of preventing and/or treating disease, especially viral diseases,most especially respiratory syncytial virus infections, comprising theadministering to a patient at risk thereof, or afflicted therewith, of atherapeutically effective amount of the antibody composition describedherein.

[0125] In one particular embodiment, a high potency neutralizingantibody of the present invention has the sequence of FIG. 3 (SEQ ID NO:101 and 102) for clone 15 with the CDRs of clone 15 given in Table 2).

[0126] It should be kept in mind that while the increased k_(on)antibodies of the present invention could be assembled from CDR regionsand non-CDR regions derived from actual neutralizing antibodies bysplicing amino acid segments together (and antibodies so assembled wouldbe within the invention disclosed herein) the antibodies of the presentinvention are most conveniently prepared by genetically engineeringappropriate gene sequences into vectors that may then be transfectedinto suitable cell lines for eventual expression of the assembledantibody molecules by the engineered cells. In fact, such recombinantprocedures were employed to prepare the antibodies disclosed herein. Inaddition, because the sequences of the chains of the high affinityantibodies are known from the disclosure herein, such antibodies couldalso be assembled by direct synthesis of the appropriate chains and thenallowed to self-assemble into tetrameric antibody structures.

General Materials and Methods

[0127] Monoclonal Antibodies

[0128] MEDI-493 is an IgG₁ (COR)/kappa (K102) humanized MAb (heavy andlight chain variable region sequences shown in FIG. 1) containing theantigen binding determinants of murine MAb 1129 [Johnson et al, J.Infect. Dis., 176, 1215-1224 (1997); Beeler and van Wyck Coelingh, J.Virol., 63, 2941-2950 (1989)].

[0129] RSV Fusion Inhibition Assay

[0130] The ability of the antibodies to block RSV-induced fusion afterviral attachment to the cells was determined in a fusion inhibitionassay. This assay was identical to the microneutralization assay, exceptthat the cells were infected with RSV (Long) for four hours prior toaddition of antibody [Taylor et al, J. Gen. Virol., 73, 2217-2223(1992)].

[0131] BIAcore Analysis

[0132] Epitope analysis of the MAbs was performed using a BIAcorebiosensor (BIAcore, Piscataway, N.J.) [Karlsson et al, J. Immunol.Methods, 145, 229-240 (1991); Johne, Mol. Biotechnol., 9, 65-71 (1998)]with a plasmin resonance microfluidics system. The antigen used for thisassay was a truncated RSV (A2) F protein (amino acids 1-526) expressedin baculovirus. Purified RSV F protein was covalently coupled to anN-hydroxysuccinimide/I-ethyl-3-[3-dimethylaminopropyl]-carbodiimideactivated CM5 sensor chip according to the manufacturer's protocol, andunreacted active ester groups were reacted with 1 M ethanolamine. Aprimary injection of either 1 μM or 10 μM MEDI-493 was followed by anHBSS wash step, and then by a secondary injection of either MEDI-493 orRHSZ19. Sensorgrams were analyzed using BIAevaluation software.

[0133] Isothermal Titration Calorimetry

[0134] The solution affinity of each MAb for RSV F protein wasdetermined by isothermal titration calorimetry [Wiseman et al, Anal.Biochem., 179, 131-137 (1989)]. A 1.4 mL solution of 4.5 μM RSV Fprotein was titrated with 5.5 μL injections of 26 μM MEDI-493 or RSHZ19.After each injection of MAb, the amount heat given off, which isproportional to the amount of binding, was measured. The antigen usedwas an RSV (A2) F protein truncate (amino acids 25-524) expressed indrosophila cells. Titrations were conducted at 44° and 55° C. to achieveoptimal signal to noise. Thermal stability of the MAbs and the F proteinat these temperatures was demonstrated by circular dichroism unfoldingexperiments. Affinities were corrected to 37° C. for comparison with invivo data using the integrated van't Hoff equation [Doyle and Hensley,Methods Enzymol., 295, 88-99 (1998)]. The van't Hoff correction is basedsolely on the F protein binding enthalpy change which was measureddirectly by calorimetry. Since the binding enthalpy changes for MEDI-493and RSHZ19 were found to be very similar, the temperature correctionsfor their Kds were nearly identical.

[0135] Cotton Rat Prophylaxis

[0136] In vivo efficacy is determined using the cotton rat model [Princeet al, J. Virol., 55, 517-520 (1985)]. Cotton rats (Sigmodon hispidus,average weight 100 grams) are anesthetized with methoxyflurane, bled,and given 0.1 mL of purified MAb by intramuscular injection (i.m.) atdoses of 5, 2.5, 1.25, or 0.625 mg/kg body weight, or bovine serumalbumin (BSA) control at 5 mg/kg body weight. Twenty-four hours lateranimals are again anesthetized, bled for serum MAb concentrationdetermination, and challenged by intranasal instillation (i.n.) of 10⁵PFU A (Long) or B (18537) strains of RSV. Four days later animals aresacrificed and their lungs were harvested. Lungs are homogenized in 10parts (wt/vol) of Hanks balanced salt solution and the resultantsuspension is used to determine pulmonary viral titers by plaque assay.Serum antibody titers at the time of challenge were determined by ananti-human IgG ELISA.

EXAMPLE 1 Kinetic Analysis of Humanized RSV Mabs by BIAcore™

[0137] The kinetics of interaction between high affinity anti-RSV Mabsand the RSV F protein was studied by surface plasmon resonance using aPharmacia BlAcore™ biosensor. A recombinant baculovirus expressing aC-terminal truncated F protein provided an abundant source of antigenfor kinetic studies. The supernatant, which contained the secreted Fprotein, was enriched approximately 20-fold by successive chromatographyon concanavalin A and Q-sepharose columns. The pooled fractions weredialyzed against 10 mM sodium citrate (pH 5.5), and concentrated toapproximately 0.1 mg/mi. In a typical experiment, an aliquot of theF-protein (100 ml) was amine-coupled to the BIAcore sensor chip. Theamount immobilized gave approximately 2000 response units (R_(max)) ofsignal when saturated with either H1129 or H1308F (prepared as in U.S.Pat. No. 5,824,307, whose disclosure is hereby incorporated byreference). This indicated that there was an equal number of “A” and “C”antigenic sites on the F-protein preparation following the couplingprocedure. Two unrelated irrelevant Mabs (RVFV 4D4 and CMV H758) showedno interaction with the immobilized F protein. A typical kinetic studyinvolved the injection of 35 ml of Mab at varying concentrations (25-300nM) in PBS buffer containing 0.05% Tween-20 (PBS/Tween). The flow ratewas maintained at 5 ml/min, giving a 7 min binding phase. Following theinjection of Mab, the flow was exchanged with PBS/Tween buffer for 30min for determining the rate of dissociation. The sensor chip wasregenerated between cycles with a 2 min pulse of 10 mM HCI. Theregeneration step caused a minimal loss of binding capacity of theimmobilized F-protein (4% loss per cycle). This small decrease did notchange the calculated values of the rate constants for binding anddissociation (also called the k_(on) and k_(off), respectively).

[0138] More specifically, for measurement of k_(assoc) (or k_(on)), Fprotein was directly immobilized by the EDC/NHS method(EDC=N-ethyl-N′-[3-diethylaminopropyl)-carbodiimide). Briefly, 4 μg/mlof F protein in 10 mM NaOAc, pH 4.0 was prepared and about a 30 μlinjection gives about 500 RU (response units) of immobilized F proteinunder the above referenced conditions. The blank flow cell (VnRimmobilized-CM dextran surface) was subtracted for kinetic analysis. Thecolumn could be regenerated using 100 mM HCI (with 72 seconds of contacttime being required for full regeneration). This treatment removed boundFab completely without damaging the immobilized antigen and could beused for over 40 regenerations. For k_(on) measurements, Fabconcentrations were 12.5 nM, 25 nM, 50 nM, 100 nM, 200 nM, and 400 nM.The dissociation phase was analyzed from 230 seconds (30 seconds afterstart of the dissociation phase) to 900 seconds. Kinetics were analyzedby 1:1 Langmuir fitting (global fitting). Measurements were done inHBS-EP buffer (10 mM HEPES, pH 7.4, 150 mM NaCl, 3 mM EDTA, 0.005% (v/v)Surfactant P20.

[0139] For measurements of combinatorial clones, as disclosed herein,the k_(on) and k_(off) were measured separately. The k_(on) was measuredat conditions that were the same as those for the single mutation clonesand was analyzed similarly.

[0140] For measuring k_(off (or k) _(dissoc)) the following conditionswere employed. Briefly, 4100 RU of F protein were immobilized (as above)with CM-dextran used as the blank. Here, 3000 RU of Fab was bound (withdissociated Fab high enough to offset machine fluctuation). HBS plus 5nM F protein (about 350-2000 times higher than the k_(dissoc) orK_(d)—the dissociation equilibrium constant) was used as buffer. Thedissociation phase was 6-15 hours at a flow rate of 5 μl/min. Under theconditions used herein, re-binding of the dissociated Fab was minimal.For further details, see the manual with the biosensor.

[0141] The binding of the high affinity anti-RSV antibodies to the Fprotein, or other epitopic sites on RSV, disclosed herein was calculatedfrom the ratio of the first order rate constant for dissociation to thesecond order rate constant for binding or association(K_(d)=k_(diss)/k_(assoc)). The value for k_(assoc) was calculated basedon the following rate equation:

dR/dt=k _(assoc) [Mab]R _(max)−(k _(assoc) [Mab]+k _(diss))R

[0142] where R and R_(max) are the response units at time t andinfinity, respectively. A plot of dr/dt as a function of R gives a slopeof (k_(assoc)[Mab]+k_(diss))—Since these slopes are linearly related tothe [Mab], the value k_(assoc) can be derived from a replot of theslopes versus [Mab]. The slope of the new line is equal to k_(assoc).Although the value of k_(diss) can be extrapolated from the Y-intercept,a more accurate value was determined by direct measurement of k_(diss).Following the injection phase of the Mab, PBS/Tween buffer flows acrossthe sensor chip. From this point, [Mab]=0. The above stated equation fordR/dt thus reduces to:

dr/dt=k _(diss) R or dR/R=k _(diss) dt

[0143] Integration of this equation then gives:

In(R ₀ /R _(t))=k _(diss) t

[0144] where R₀/R_(t)) are the response units at time 0 (start ofdissociation phase) and t, respectively. Lastly, plotting In(R₀/R_(t))as a function of t gives a slope of k_(diss).

[0145] In the preferred embodiment herein, the numerical values fromsuch antibody variants are shown in Table 3.

[0146] For the clones in Tables 2 and 3, the reference clone is the Fabfragment with the sequences shown in FIG. 2 and CDRs shown in Table 1.Clones 1-15 are Fab fragments having the framework sequences of FIG. 2and the indicated CDR combinations of clones 1-15 of Table 2 (where the“X” indicates a high potency CDR (i.e., a CDR whose presence versus thereference sequence results in high potency and higher potency than thereference Fab)). Where no “X” appears next to the CDR of Table 2, thesequence is just the corresponding sequence of the reference Fab (fromTable 1 and FIG. 2).

[0147] Results in Table 4 compare Fab fragments and full tetramericantibody molecules as related by IC₅₀ values (or the concentration inμg/ml giving 50% inhibition versus controls similar to those for Table3). Clone 16 of the table is the reference antibody with CDRs describedin Table 2.

[0148] Table 3. Summary of Kinetic Constants for High PotencyAntibodies. TABLE 3 Clone No. K_(on) × 10⁵ (M⁻¹s⁻¹) K_(off) × 10⁻⁴ (s⁻¹)EC₅₀ (nM) Ref. 1.85 6.5 3.52  1 3.65 3.26 2.26  2 5.31 4.22 5.05  3 6.054.22 4.70  4 7.57 4.62 3.55  5 4.16 3.06 2.61  6 1.85 3.20 2.88  7 3.702.51 1.59  8 3.75 2.73 2.67  9 6.63 2.82 0.29 10 5.27 2.99 1.06 11 5.717.17 20.9 12 7.9 4.53 3.24 13 7.43 2.30 0.81 14 7.35 2.50 2.23 15 7.812.80 0.56 16 2.04 7.35 6.12 17 1.09 2.49 2.7

[0149] TABLE 4 End Point RSV Microneutralization Titers of High On RateMutant IgGs and Fabs Fold Mean IC50 Standard Difference Number of MeanIC50 Standard Fold (Control) (Control (Control Assay Type Clone No.μg/ml IC50 Difference μg/ml IC50) IC50) Repeats IgG 16 0.4527 0.208 —0.5351 0.238 — 8 ″ 24 0.0625 0.0268  7 0.0645 0.0223  8 3 ″ 18 0.03420.022 13 0.0354 0.0187 15 4 ″ 23 0.0217 0.0331 21 0.0289 0.0110 19 5 ″21 0.0231 0.0141 20 0.0223 0.0083 24 6 ″ 20 0.0337 0.0309 13 0.03830.0283 14 5 ″ 25 0.0357 0.0316 13 0.0354 0.0261 15 7 ″ 22 0.0242 0.016319 0.0235 0.0076 23 7 ″ 26 0.0376 0.0268 12 0.0375 0.0213 14 6 ″ 190.0171 0.0018 27 0.0154 0.00417 35 2 Fab 12 0.157 —  3 0.125 —  4 1 ″ 270.0179 — 25 0.0171 — 31 1 ″ 11 >1.00 — — >1.00 — — 1 ″  9 0.0407 0.011211 0.0326 0.009 16 2 ″ 28 0.177 —  3 0.157 — 34 1 ″ 13 0.0287 0.00417 160.0310 0.00982 17 2 ″ 10 0.0464 0.00791 10 0.0351 0.0126 15 2 ″ 150.0264 0.00141 17 0.0258 0.00071 21 2 ″ 29 0.0414 — 11 0.0411 — 13 1 ″14 0.120 0.0222  4 0.1022 0.0260  5 2 ″ 30 0.194 0.462  2 0.176 0.0625 3 2

[0150] Clones 16 and 17 of Table 3 are actual monoclonal antibodies withthe framework sequences of FIG. 1 and constant regions as described inJohnson et al (1997). The framework sequences of these antibodies maydiffer slightly from those of the Fab fragments.

[0151] Clones 18 to 26 of Table 4 are tetrameric antibody moleculessimilar to clones 16 and 17 but having high potency CDR sequences.Antibody clone 21 has the same CDR sequences as Fab clone 9, antibodyclone 22 has the same CDR sequences as Fab clone 10, antibody clone 23has the same CDR sequences as Fab clone 11, antibody clone 24 has thesame CDR sequences as Fab clone 12, antibody clone 25 has the same CDRsequences as Fab clone 13, and antibody clone 26 has the same CDRsequences as Fab clone 15. Antibody clones 18, 19 and 20 of Table 3 arefull length tetrameric antibodies with CDR combinations given in Table2. The framework sequences of these antibodies may differ slightly fromthose of the Fab fragments.

[0152] The underlined amino acids of the CDR sequences of Table 2represent the amino acid residues located at the key locations withinthe high potency CDRs of the high potency antibodies produced by themethods of the present invention. For example, to increase the potencyof an antibody by producing a higher k_(on) value, the amino acidslocated at the key positions as taught herein by the bold and underlinedresidues in Table 1 for the reference antibody would be replaced by theamino acids listed under CDRs in Table 2 (and also bold and underlined).Thus, these one letter codes represent the amino acids replacing thereference amino acids at the key positions (or critical positions) ofthe CDRs shown in FIG. 2 (residues in bold in the sequences of Table 2)for a reference antibody whose potency is to be increased.

[0153] For the clones of Table 4, clone 18 has the full length sequencesgiven by SEQ ID NO: 41 (heavy chain) and 42 (light chain), clone 19 hasthe full length sequences given by SEQ ID NO: 45 (heavy chain) and 46(light chain), clone 20 has the full length sequences given by SEQ IDNO: 47 (heavy chain) and 48 (light chain), clone 21 has the full lengthsequences given by SEQ ID NO: 51 (heavy chain) and 52 (light chain),clone 22 has the full length sequences given by SEQ ID NO: 53 (heavychain) and 54 (light chain), clone 23 has the full length sequencesgiven by SEQ ID NO: 49 (heavy chain) and 50 (light chain), clone 24 hasthe full length sequences given by SEQ ID NO: 43 (heavy chain) and 44(light chain), clone 25 has the full length sequences given by SEQ IDNO: 37 (heavy chain) and 38 (light chain), and clone 26 has the fulllength sequences given by SEQ ID NO: 39 (heavy chain) and 40 (lightchain),

[0154] Here, clone 18 (IgG) and clone 27 (Fab) have the same CDRs, clone19 (IgG) and clone 29 (Fab) have the same CDRs, clone 20 (IgG) and clone28 (Fab) have the same CDRs, clone 21 (IgG) and clone 9 (Fab) have thesame CDRs, clone 21 (IgG) and clone 9 (Fab) have the same CDRs, clone 21(IgG) and clone 9 (Fab) have the same CDRs, clone 22 (IgG) and clone 10(Fab) have the same CDRs, clone 23 (IgG) and clone 11 (Fab) have thesame CDRs, clone 24 (IgG) and clone 12 (Fab) have the same CDRs, clone25 (IgG) and clone 13 (Fab) have the same CDRs, clone 26 (IgG) and clone15 (Fab) have the same CDRs. Thus, the data of Table 4 correlates theactivity of Fab fragments with that of a complete antibody molecule.

[0155] Thus, the present invention includes full tetrameric high potencyneutralizing antibodies wherein said antibody has a heavy chain aminoacid sequence selected from the group consisting of SEQ ID NO: 37, 39,41, 45, 47, 49, 51 and 53, and a light chain amino acid sequenceselected from the group consisting of SEQ ID NO: 38, 40, 42, 44, 46, 48,50, 52 and 54, preferably where said antibodies are the antibodies ofclones 18-26.

EXAMPLE 2 Microneutralization Assay

[0156] Neutralization of the antibodies of the present invention weredetermined by microneutralization assay. This microneutralization assayis a modification of the procedures described by Anderson et al[“Microneutralization test for respiratory syncytial virus based on anenzyme immunoassay, J. Clin. Microbiol. 22, 1050-1052 (1985), thedisclosure of which is hereby incorporated by reference in itsentirety]. The procedure used here is described in Johnson et al [J.Infectious Diseases, 180, 35-40 (1999), the disclosure of which ishereby incorporated by reference in its entirety]. Antibody dilutionswere made in triplicate using a 96-well plate. Ten TCID₅₀ of respiratorysyncytial virus (RSV—Long strain) were incubated with serial dilutionsof the antibody (or Fabs) to be tested for 2 hours at 37° C. in thewells of a 96-well plate. RSV susceptible HEp-2 cells (2.5×10⁴) werethen added to each well and cultured for 5 days at 37° C. in 5% CO₂.After 5 days, the medium was aspirated and cells were washed and fixedto the plates with 80% methanol and 20% PBS. RSV replication was thendetermined by F protein expression. Fixed cells were incubated with abiotin-conjugated anti-F protein monoclonal antibody (pan F protein,C-site-specific MAb 133-1H) washed and horseradish peroxidase conjugatedavidin was added to the wells. The wells were washed again and turnoverof substrate TMB (thionitrobenzoic acid) was measured at 450 nm. Theneutralizing titer was expressed as the antibody concentration thatcaused at least 50% reduction in absorbency at 450 nm (the OD₄₅₀) fromvirus-only control cells.

1 59 1 106 PRT Artificial Sequence Description of ArtificialSequenceLight chain variable region sequence of Medi-493 humanizedantibody. 1 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr Leu Ser Ala Ser ValGly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys Lys Cys Gln Leu Ser Val GlyTyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu LeuIle Tyr 35 40 45 Asp Thr Ser Lys Leu Ala Ser Gly Val Pro Ser Arg Phe SerGly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr Ile Ser Ser Leu GlnPro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe Gln Gly Ser Gly TyrPro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys Leu Glu Ile Lys 100 105 2120 PRT Artificial Sequence Description of Artificial SequenceHeavychain variable region sequence of Medi-493 humanized antibody. 2 Gln ValThr Leu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro Thr Gln 1 5 10 15 ThrLeu Thr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu Ser Thr Ser 20 25 30 GlyMet Ser Val Gly Trp Ile Arg Gln Pro Pro Gly Lys Ala Leu Glu 35 40 45 TrpLeu Ala Asp Ile Trp Trp Asp Asp Lys Lys Asp Tyr Asn Pro Ser 50 55 60 LeuLys Ser Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys Asn Gln Val 65 70 75 80Val Leu Lys Val Thr Asn Met Asp Pro Ala Asp Thr Ala Thr Tyr Tyr 85 90 95Cys Ala Arg Ser Met Ile Thr Asn Trp Tyr Phe Asp Val Trp Gly Ala 100 105110 Gly Thr Thr Val Thr Val Ser Ser 115 120 3 106 PRT ArtificialSequence Description of Artificial SequenceLight chain variable regionsequence of a humanized antibody. 3 Asp Ile Gln Met Thr Gln Ser Pro SerThr Leu Ser Ala Ser Val Gly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys SerAla Ser Ser Ser Val Gly Tyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro GlyLys Ala Pro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Ser Lys Leu Ala Ser GlyVal Pro Ser Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr LeuThr Ile Ser Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr CysPhe Gln Gly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys ValGlu Ile Lys 100 105 4 120 PRT Artificial Sequence Description ofArtificial SequenceHeavy chain variable region sequence of a humanizedantibody. 4 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro ThrGln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu SerThr Ser 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln Pro Pro Gly Lys AlaLeu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Asp Lys Lys Asp Tyr AsnPro Ser 50 55 60 Leu Lys Ser Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys AsnGln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp Pro Ala Asp Thr AlaThr Tyr Tyr 85 90 95 Cys Ala Arg Ser Met Ile Thr Asn Trp Tyr Phe Asp ValTrp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser Ser 115 120 5 10 PRTArtificial Sequence Description of Artificial SequenceLight chain CDRreference sequence. 5 Ser Ala Ser Ser Ser Val Gly Tyr Met His 1 5 10 6 7PRT Artificial Sequence Description of Artificial SequenceLight chainCDR reference sequence. 6 Asp Thr Ser Lys Leu Ala Ser 1 5 7 9 PRTArtificial Sequence Description of Artificial SequenceLight chain CDRreference sequence. 7 Phe Gln Gly Ser Gly Tyr Pro Phe Thr 1 5 8 7 PRTArtificial Sequence Description of Artificial SequenceHeavy Chain CDRreference sequence. 8 Thr Ser Gly Met Ser Val Gly 1 5 9 16 PRTArtificial Sequence Description of Artificial SequenceHeavy Chain CDRreference sequence. 9 Asp Ile Trp Trp Asp Asp Lys Lys Asp Tyr Asn ProSer Leu Lys Ser 1 5 10 15 10 10 PRT Artificial Sequence Description ofArtificial SequenceHeavy Chain CDR reference sequence. 10 Ser Met IleThr Asn Trp Tyr Phe Asp Val 1 5 10 11 10 PRT Artificial SequenceDescription of Artificial SequenceHigh potency CDR sequence. 11 Ser AlaSer Ser Arg Val Gly Tyr Met His 1 5 10 12 10 PRT Artificial SequenceDescription of Artificial SequenceHigh potency CDR sequence. 12 Ser LeuSer Ser Arg Val Gly Tyr Met His 1 5 10 13 10 PRT Artificial SequenceDescription of Artificial SequenceHigh potency CDR sequence. 13 Ser ProSer Ser Arg Val Gly Tyr Met His 1 5 10 14 7 PRT Artificial SequenceDescription of Artificial SequenceHigh potency CDR sequence. 14 Asp ThrPhe Lys Leu Thr Ser 1 5 15 7 PRT Artificial Sequence Description ofArtificial SequenceHigh potency CDR sequence. 15 Asp Thr Phe Lys Leu AlaSer 1 5 16 7 PRT Artificial Sequence Description of ArtificialSequenceHigh potency CDR sequence. 16 Asp Thr Tyr Lys Gln Thr Ser 1 5 177 PRT Artificial Sequence Description of Artificial SequenceHigh potencyCDR sequence. 17 Asp Thr Arg Tyr Leu Ser Ser 1 5 18 7 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 18Asp Thr Arg Gly Leu Pro Ser 1 5 19 7 PRT Artificial Sequence Descriptionof Artificial SequenceHigh potency CDR sequence. 19 Asp Thr Met Arg LeuAla Ser 1 5 20 7 PRT Artificial Sequence Description of ArtificialSequenceHigh potency CDR sequence. 20 Asp Thr Phe Lys Leu Ser Ser 1 5 217 PRT Artificial Sequence Description of Artificial SequenceHigh potencyCDR sequence. 21 Asp Thr Tyr Arg His Ser Ser 1 5 22 7 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 22Asp Thr Met Tyr Gln Ser Ser 1 5 23 9 PRT Artificial Sequence Descriptionof Artificial SequenceHigh potency CDR sequence. 23 Phe Gln Gly Ser PheTyr Pro Phe Thr 1 5 24 7 PRT Artificial Sequence Description ofArtificial SequenceHigh potency CDR sequence. 24 Thr Ala Gly Met Ser ValGly 1 5 25 7 PRT Artificial Sequence Description of ArtificialSequenceHigh potency CDR sequence. 25 Thr Pro Gly Met Ser Val Gly 1 5 2616 PRT Artificial Sequence Description of Artificial SequenceHighpotency CDR sequence. 26 Asp Ile Trp Trp Asp Asp Lys Lys His Tyr Asn ProSer Leu Lys Asp 1 5 10 15 27 16 PRT Artificial Sequence Description ofArtificial SequenceHigh potency CDR sequence. 27 Asp Ile Trp Trp Asp GlyLys Lys His Tyr Asn Pro Ser Leu Lys Asp 1 5 10 15 28 16 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 28Asp Ile Trp Trp Asp Gly Lys Lys Asp Tyr Asn Pro Ser Leu Lys Asp 1 5 1015 29 16 PRT Artificial Sequence Description of Artificial SequenceHighpotency CDR sequence. 29 Asp Ile Trp Trp Asp Asp Lys Lys His Tyr Asn ProSer Leu Lys Asp 1 5 10 15 30 16 PRT Artificial Sequence Description ofArtificial SequenceHigh potency CDR sequence. 30 Asp Ile Trp Trp Asp GlyLys Lys Ser Tyr Asn Pro Ser Leu Lys Asp 1 5 10 15 31 10 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 31Asp Met Ile Phe Asn Phe Tyr Phe Asp Val 1 5 10 32 10 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 32Asp Met Ile Phe Asn Trp Tyr Phe Asp Val 1 5 10 33 10 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 33Ser Met Ile Thr Asn Phe Tyr Phe Asp Val 1 5 10 34 10 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 34Asp Met Ile Phe Asn Phe Tyr Phe Asp Val 1 5 10 35 106 PRT ArtificialSequence Description of Artificial Sequence Heavy chain of high potencyantibody. 35 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr Leu Ser Ala Ser ValGly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys Ser Leu Ser Ser Arg Val GlyTyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu LeuIle Tyr 35 40 45 Asp Thr Met Tyr Gln Ser Ser Gly Val Pro Ser Arg Phe SerGly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr Ile Ser Ser Leu GlnPro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe Gln Gly Ser Gly TyrPro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys Val Glu Ile Lys 100 105 36120 PRT Artificial Sequence Description of Artificial Sequence Lightchain of high potency antibody. 36 Gln Val Thr Leu Arg Glu Ser Gly ProAla Leu Val Lys Pro Thr Gln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr PheSer Gly Phe Ser Leu Ser Thr Ala 20 25 30 Gly Met Ser Val Gly Trp Ile ArgGln Pro Pro Gly Lys Ala Leu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp AspGly Lys Lys Ser Tyr Asn Pro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile SerLys Asp Thr Ser Lys Asn Gln Val 65 70 75 80 Val Leu Lys Val Thr Asn MetAsp Pro Ala Asp Thr Ala Thr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile PheAsn Phe Tyr Phe Asp Val Trp Gly Gln 100 105 110 Gly Thr Thr Val Thr ValSer Ser 115 120 37 450 PRT Artificial Sequence Description of ArtificialSequence Heavy chain of high potency antibody. 37 Gln Val Thr Leu ArgGlu Ser Gly Pro Ala Leu Val Lys Pro Thr Gln 1 5 10 15 Thr Leu Thr LeuThr Cys Thr Phe Ser Gly Phe Ser Leu Ser Thr Ala 20 25 30 Gly Met Ser ValGly Trp Ile Arg Gln Pro Pro Gly Lys Ala Leu Glu 35 40 45 Trp Leu Ala AspIle Trp Trp Asp Gly Lys Lys Asp Tyr Asn Pro Ser 50 55 60 Leu Lys Asp ArgLeu Thr Ile Ser Lys Asp Thr Ser Lys Asn Gln Val 65 70 75 80 Val Leu LysVal Thr Asn Met Asp Pro Ala Asp Thr Ala Thr Tyr Tyr 85 90 95 Cys Ala ArgAsp Met Ile Phe Asn Phe Tyr Phe Asp Val Trp Gly Gln 100 105 110 Gly ThrThr Val Thr Val Ser Ser Ala Ser Thr Lys Gly Pro Ser Val 115 120 125 PhePro Leu Ala Pro Ser Ser Lys Ser Thr Ser Gly Gly Thr Ala Ala 130 135 140Leu Gly Cys Leu Val Lys Asp Tyr Phe Pro Glu Pro Val Thr Val Ser 145 150155 160 Trp Asn Ser Gly Ala Leu Thr Ser Gly Val His Thr Phe Pro Ala Val165 170 175 Leu Gln Ser Ser Gly Leu Tyr Ser Leu Ser Ser Val Val Thr ValPro 180 185 190 Ser Ser Ser Leu Gly Thr Gln Thr Tyr Ile Cys Asn Val AsnHis Lys 195 200 205 Pro Ser Asn Thr Lys Val Asp Lys Arg Val Glu Pro LysSer Cys Asp 210 215 220 Lys Thr His Thr Cys Pro Pro Cys Pro Ala Pro GluLeu Leu Gly Gly 225 230 235 240 Pro Ser Val Phe Leu Phe Pro Pro Lys ProLys Asp Thr Leu Met Ile 245 250 255 Ser Arg Thr Pro Glu Val Thr Cys ValVal Val Asp Val Ser His Glu 260 265 270 Asp Pro Glu Val Lys Phe Asn TrpTyr Val Asp Gly Val Glu Val His 275 280 285 Asn Ala Lys Thr Lys Pro ArgGlu Glu Gln Tyr Asn Ser Thr Tyr Arg 290 295 300 Val Val Ser Val Leu ThrVal Leu His Gln Asp Trp Leu Asn Gly Lys 305 310 315 320 Glu Tyr Lys CysLys Val Ser Asn Lys Ala Leu Pro Ala Pro Ile Glu 325 330 335 Lys Thr IleSer Lys Ala Lys Gly Gln Pro Arg Glu Pro Gln Val Tyr 340 345 350 Thr LeuPro Pro Ser Arg Glu Glu Met Thr Lys Asn Gln Val Ser Leu 355 360 365 ThrCys Leu Val Lys Gly Phe Tyr Pro Ser Asp Ile Ala Val Glu Trp 370 375 380Glu Ser Asn Gly Gln Pro Glu Asn Asn Tyr Lys Thr Thr Pro Pro Val 385 390395 400 Leu Asp Ser Asp Gly Ser Phe Phe Leu Tyr Ser Lys Leu Thr Val Asp405 410 415 Lys Ser Arg Trp Gln Gln Gly Asn Val Phe Ser Cys Ser Val MetHis 420 425 430 Glu Ala Leu His Asn His Tyr Thr Gln Lys Ser Leu Ser LeuSer Pro 435 440 445 Gly Lys 450 38 213 PRT Artificial SequenceDescription of Artificial Sequence Light chain of high potency antibody.38 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 510 15 Asp Arg Val Thr Ile Thr Cys Ser Ala Ser Ser Arg Val Gly Tyr Met 2025 30 His Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 3540 45 Asp Thr Phe Lys Leu Ser Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 5055 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 6570 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr85 90 95 Phe Gly Gly Gly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro100 105 110 Ser Val Phe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser GlyThr 115 120 125 Ala Ser Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg GluAla Lys 130 135 140 Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly AsnSer Gln Glu 145 150 155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser ThrTyr Ser Leu Ser Ser 165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr GluLys His Lys Val Tyr Ala 180 185 190 Cys Glu Val Thr His Gln Gly Leu SerSer Pro Val Thr Lys Ser Phe 195 200 205 Asn Arg Gly Glu Cys 210 39 450PRT Artificial Sequence Description of Artificial Sequence Heavy chainof high potency antibody. 39 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala LeuVal Lys Pro Thr Gln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser GlyPhe Ser Leu Ser Thr Ala 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln ProPro Gly Lys Ala Leu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Gly LysLys Ser Tyr Asn Pro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys AspThr Ser Lys Asn Gln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp ProAla Asp Thr Ala Thr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn PheTyr Phe Asp Val Trp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser SerAla Ser Thr Lys Gly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser SerLys Ser Thr Ser Gly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val LysAsp Tyr Phe Pro Glu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser GlyAla Leu Thr Ser Gly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln SerSer Gly Leu Tyr Ser Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser SerSer Leu Gly Thr Gln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 ProSer Asn Thr Lys Val Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220Lys Thr His Thr Cys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230235 240 Pro Ser Val Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile245 250 255 Ser Arg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser HisGlu 260 265 270 Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val GluVal His 275 280 285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn SerThr Tyr Arg 290 295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp TrpLeu Asn Gly Lys 305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys AlaLeu Pro Ala Pro Ile Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly GlnPro Arg Glu Pro Gln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu GluMet Thr Lys Asn Gln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly PheTyr Pro Ser Asp Ile Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln ProGlu Asn Asn Tyr Lys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser AspGly Ser Phe Phe Leu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser ArgTrp Gln Gln Gly Asn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu AlaLeu His Asn His Tyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 GlyLys 450 40 213 PRT Artificial Sequence Description of ArtificialSequence Light chain of high potency antibody. 40 Asp Ile Gln Met ThrGln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 5 10 15 Asp Arg Val ThrIle Thr Cys Ser Leu Ser Ser Arg Val Gly Tyr Met 20 25 30 His Trp Tyr GlnGln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Met TyrGln Ser Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly ThrGlu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe AlaThr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly GlyGly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro 100 105 110 Ser ValPhe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser Gly Thr 115 120 125 AlaSer Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr Glu Lys His Lys Val TyrAla 180 185 190 Cys Glu Val Thr His Gln Gly Leu Ser Ser Pro Val Thr LysSer Phe 195 200 205 Asn Arg Gly Glu Cys 210 41 450 PRT ArtificialSequence Description of Artificial Sequence Heavy chain of high potencyantibody. 41 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro ThrGln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu SerThr Ala 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln Pro Pro Gly Lys AlaLeu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Gly Lys Lys Ser Tyr AsnPro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys AsnGln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp Pro Ala Asp Thr AlaThr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn Phe Tyr Phe Asp ValTrp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser Ser Ala Ser Thr LysGly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser Ser Lys Ser Thr SerGly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val Lys Asp Tyr Phe ProGlu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser Gly Ala Leu Thr SerGly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln Ser Ser Gly Leu TyrSer Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser Ser Ser Leu Gly ThrGln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 Pro Ser Asn Thr LysVal Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220 Lys Thr His ThrCys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230 235 240 Pro SerVal Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile 245 250 255 SerArg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser His Glu 260 265 270Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val Glu Val His 275 280285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn Ser Thr Tyr Arg 290295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp Trp Leu Asn Gly Lys305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys Ala Leu Pro Ala ProIle Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly Gln Pro Arg Glu ProGln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu Glu Met Thr Lys AsnGln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly Phe Tyr Pro Ser AspIle Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln Pro Glu Asn Asn TyrLys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser Asp Gly Ser Phe PheLeu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser Arg Trp Gln Gln GlyAsn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu Ala Leu His Asn HisTyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 Gly Lys 450 42 213PRT Artificial Sequence Description of Artificial Sequence Light chainof high potency antibody. 42 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr LeuSer Ala Ser Val Gly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys Leu Pro SerSer Arg Val Gly Tyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro Gly Lys AlaPro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Met Tyr Gln Ser Ser Gly Val ProSer Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr IleSer Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe GlnGly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys Val Glu IleLys Arg Thr Val Ala Ala Pro 100 105 110 Ser Val Phe Ile Phe Pro Pro SerAsp Glu Gln Leu Lys Ser Gly Thr 115 120 125 Ala Ser Val Val Cys Leu LeuAsn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140 Val Gln Trp Lys Val AspAsn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150 155 160 Ser Val Thr GluGln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser 165 170 175 Thr Leu ThrLeu Ser Lys Ala Asp Tyr Glu Lys His Lys Val Tyr Ala 180 185 190 Cys GluVal Thr His Gln Gly Leu Ser Ser Pro Val Thr Lys Ser Phe 195 200 205 AsnArg Gly Glu Cys 210 43 450 PRT Artificial Sequence Description ofArtificial Sequence Heavy chain of high potency antibody. 43 Gln Val ThrLeu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro Thr Gln 1 5 10 15 Thr LeuThr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu Ser Thr Ala 20 25 30 Gly MetSer Val Gly Trp Ile Arg Gln Pro Pro Gly Lys Ala Leu Glu 35 40 45 Trp LeuAla Asp Ile Trp Trp Asp Gly Lys Lys His Tyr Asn Pro Ser 50 55 60 Leu LysAsp Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys Asn Gln Val 65 70 75 80 ValLeu Lys Val Thr Asn Met Asp Pro Ala Asp Thr Ala Thr Tyr Tyr 85 90 95 CysAla Arg Asp Met Ile Phe Asn Trp Tyr Phe Asp Val Trp Gly Gln 100 105 110Gly Thr Thr Val Thr Val Ser Ser Ala Ser Thr Lys Gly Pro Ser Val 115 120125 Phe Pro Leu Ala Pro Ser Ser Lys Ser Thr Ser Gly Gly Thr Ala Ala 130135 140 Leu Gly Cys Leu Val Lys Asp Tyr Phe Pro Glu Pro Val Thr Val Ser145 150 155 160 Trp Asn Ser Gly Ala Leu Thr Ser Gly Val His Thr Phe ProAla Val 165 170 175 Leu Gln Ser Ser Gly Leu Tyr Ser Leu Ser Ser Val ValThr Val Pro 180 185 190 Ser Ser Ser Leu Gly Thr Gln Thr Tyr Ile Cys AsnVal Asn His Lys 195 200 205 Pro Ser Asn Thr Lys Val Asp Lys Arg Val GluPro Lys Ser Cys Asp 210 215 220 Lys Thr His Thr Cys Pro Pro Cys Pro AlaPro Glu Leu Leu Gly Gly 225 230 235 240 Pro Ser Val Phe Leu Phe Pro ProLys Pro Lys Asp Thr Leu Met Ile 245 250 255 Ser Arg Thr Pro Glu Val ThrCys Val Val Val Asp Val Ser His Glu 260 265 270 Asp Pro Glu Val Lys PheAsn Trp Tyr Val Asp Gly Val Glu Val His 275 280 285 Asn Ala Lys Thr LysPro Arg Glu Glu Gln Tyr Asn Ser Thr Tyr Arg 290 295 300 Val Val Ser ValLeu Thr Val Leu His Gln Asp Trp Leu Asn Gly Lys 305 310 315 320 Glu TyrLys Cys Lys Val Ser Asn Lys Ala Leu Pro Ala Pro Ile Glu 325 330 335 LysThr Ile Ser Lys Ala Lys Gly Gln Pro Arg Glu Pro Gln Val Tyr 340 345 350Thr Leu Pro Pro Ser Arg Glu Glu Met Thr Lys Asn Gln Val Ser Leu 355 360365 Thr Cys Leu Val Lys Gly Phe Tyr Pro Ser Asp Ile Ala Val Glu Trp 370375 380 Glu Ser Asn Gly Gln Pro Glu Asn Asn Tyr Lys Thr Thr Pro Pro Val385 390 395 400 Leu Asp Ser Asp Gly Ser Phe Phe Leu Tyr Ser Lys Leu ThrVal Asp 405 410 415 Lys Ser Arg Trp Gln Gln Gly Asn Val Phe Ser Cys SerVal Met His 420 425 430 Glu Ala Leu His Asn His Tyr Thr Gln Lys Ser LeuSer Leu Ser Pro 435 440 445 Gly Lys 450 44 213 PRT Artificial SequenceDescription of Artificial Sequence Light chain of high potency antibody.44 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 510 15 Asp Arg Val Thr Ile Thr Cys Ser Leu Ser Ser Arg Val Gly Tyr Met 2025 30 His Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 3540 45 Asp Thr Phe Lys Leu Ser Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 5055 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 6570 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr85 90 95 Phe Gly Gly Gly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro100 105 110 Ser Val Phe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser GlyThr 115 120 125 Ala Ser Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg GluAla Lys 130 135 140 Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly AsnSer Gln Glu 145 150 155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser ThrTyr Ser Leu Ser Ser 165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr GluLys His Lys Val Tyr Ala 180 185 190 Cys Glu Val Thr His Gln Gly Leu SerSer Pro Val Thr Lys Ser Phe 195 200 205 Asn Arg Gly Glu Cys 210 45 450PRT Artificial Sequence Description of Artificial Sequence Heavy chainof high potency antibody. 45 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala LeuVal Lys Pro Thr Gln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser GlyPhe Ser Leu Ser Thr Ala 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln ProPro Gly Lys Ala Leu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Asp LysLys His Tyr Asn Pro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys AspThr Ser Lys Asn Gln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp ProAla Asp Thr Ala Thr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn PheTyr Phe Asp Val Trp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser SerAla Ser Thr Lys Gly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser SerLys Ser Thr Ser Gly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val LysAsp Tyr Phe Pro Glu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser GlyAla Leu Thr Ser Gly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln SerSer Gly Leu Tyr Ser Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser SerSer Leu Gly Thr Gln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 ProSer Asn Thr Lys Val Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220Lys Thr His Thr Cys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230235 240 Pro Ser Val Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile245 250 255 Ser Arg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser HisGlu 260 265 270 Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val GluVal His 275 280 285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn SerThr Tyr Arg 290 295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp TrpLeu Asn Gly Lys 305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys AlaLeu Pro Ala Pro Ile Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly GlnPro Arg Glu Pro Gln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu GluMet Thr Lys Asn Gln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly PheTyr Pro Ser Asp Ile Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln ProGlu Asn Asn Tyr Lys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser AspGly Ser Phe Phe Leu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser ArgTrp Gln Gln Gly Asn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu AlaLeu His Asn His Tyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 GlyLys 450 46 213 PRT Artificial Sequence Description of ArtificialSequence Light chain of high potency antibody. 46 Asp Ile Gln Met ThrGln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 5 10 15 Asp Arg Val ThrIle Thr Cys Ser Ala Ser Ser Arg Val Gly Tyr Met 20 25 30 His Trp Tyr GlnGln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Phe PheLeu Asp Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly ThrGlu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe AlaThr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly GlyGly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro 100 105 110 Ser ValPhe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser Gly Thr 115 120 125 AlaSer Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr Glu Lys His Lys Val TyrAla 180 185 190 Cys Glu Val Thr His Gln Gly Leu Ser Ser Pro Val Thr LysSer Phe 195 200 205 Asn Arg Gly Glu Cys 210 47 450 PRT ArtificialSequence Description of Artificial Sequence Heavy chain of high potencyantibody. 47 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro ThrGln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu SerThr Ala 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln Pro Pro Gly Lys AlaLeu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Asp Lys Lys Ser Tyr AsnPro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys AsnGln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp Pro Ala Asp Thr AlaThr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn Trp Tyr Phe Asp ValTrp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser Ser Ala Ser Thr LysGly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser Ser Lys Ser Thr SerGly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val Lys Asp Tyr Phe ProGlu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser Gly Ala Leu Thr SerGly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln Ser Ser Gly Leu TyrSer Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser Ser Ser Leu Gly ThrGln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 Pro Ser Asn Thr LysVal Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220 Lys Thr His ThrCys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230 235 240 Pro SerVal Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile 245 250 255 SerArg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser His Glu 260 265 270Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val Glu Val His 275 280285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn Ser Thr Tyr Arg 290295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp Trp Leu Asn Gly Lys305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys Ala Leu Pro Ala ProIle Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly Gln Pro Arg Glu ProGln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu Glu Met Thr Lys AsnGln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly Phe Tyr Pro Ser AspIle Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln Pro Glu Asn Asn TyrLys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser Asp Gly Ser Phe PheLeu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser Arg Trp Gln Gln GlyAsn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu Ala Leu His Asn HisTyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 Gly Lys 450 48 213PRT Artificial Sequence Description of Artificial Sequence Light chainof high potency antibody. 48 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr LeuSer Ala Ser Val Gly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys Ser Pro SerSer Arg Val Gly Tyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro Gly Lys AlaPro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Arg Tyr Gln Ser Ser Gly Val ProSer Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr IleSer Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe GlnGly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys Val Glu IleLys Arg Thr Val Ala Ala Pro 100 105 110 Ser Val Phe Ile Phe Pro Pro SerAsp Glu Gln Leu Lys Ser Gly Thr 115 120 125 Ala Ser Val Val Cys Leu LeuAsn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140 Val Gln Trp Lys Val AspAsn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150 155 160 Ser Val Thr GluGln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser 165 170 175 Thr Leu ThrLeu Ser Lys Ala Asp Tyr Glu Lys His Lys Val Tyr Ala 180 185 190 Cys GluVal Thr His Gln Gly Leu Ser Ser Pro Val Thr Lys Ser Phe 195 200 205 AsnArg Gly Glu Cys 210 49 450 PRT Artificial Sequence Description ofArtificial Sequence Heavy chain of high potency antibody. 49 Gln Val ThrLeu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro Thr Gln 1 5 10 15 Thr LeuThr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu Ser Thr Pro 20 25 30 Gly MetSer Val Gly Trp Ile Arg Gln Pro Pro Gly Lys Ala Leu Glu 35 40 45 Trp LeuAla Asp Ile Trp Trp Asp Gly Lys Lys His Tyr Asn Pro Ser 50 55 60 Leu LysAsp Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys Asn Gln Val 65 70 75 80 ValLeu Lys Val Thr Asn Met Asp Pro Ala Asp Thr Ala Thr Tyr Tyr 85 90 95 CysAla Arg Asp Met Ile Phe Asn Trp Tyr Phe Asp Val Trp Gly Gln 100 105 110Gly Thr Thr Val Thr Val Ser Ser Ala Ser Thr Lys Gly Pro Ser Val 115 120125 Phe Pro Leu Ala Pro Ser Ser Lys Ser Thr Ser Gly Gly Thr Ala Ala 130135 140 Leu Gly Cys Leu Val Lys Asp Tyr Phe Pro Glu Pro Val Thr Val Ser145 150 155 160 Trp Asn Ser Gly Ala Leu Thr Ser Gly Val His Thr Phe ProAla Val 165 170 175 Leu Gln Ser Ser Gly Leu Tyr Ser Leu Ser Ser Val ValThr Val Pro 180 185 190 Ser Ser Ser Leu Gly Thr Gln Thr Tyr Ile Cys AsnVal Asn His Lys 195 200 205 Pro Ser Asn Thr Lys Val Asp Lys Arg Val GluPro Lys Ser Cys Asp 210 215 220 Lys Thr His Thr Cys Pro Pro Cys Pro AlaPro Glu Leu Leu Gly Gly 225 230 235 240 Pro Ser Val Phe Leu Phe Pro ProLys Pro Lys Asp Thr Leu Met Ile 245 250 255 Ser Arg Thr Pro Glu Val ThrCys Val Val Val Asp Val Ser His Glu 260 265 270 Asp Pro Glu Val Lys PheAsn Trp Tyr Val Asp Gly Val Glu Val His 275 280 285 Asn Ala Lys Thr LysPro Arg Glu Glu Gln Tyr Asn Ser Thr Tyr Arg 290 295 300 Val Val Ser ValLeu Thr Val Leu His Gln Asp Trp Leu Asn Gly Lys 305 310 315 320 Glu TyrLys Cys Lys Val Ser Asn Lys Ala Leu Pro Ala Pro Ile Glu 325 330 335 LysThr Ile Ser Lys Ala Lys Gly Gln Pro Arg Glu Pro Gln Val Tyr 340 345 350Thr Leu Pro Pro Ser Arg Glu Glu Met Thr Lys Asn Gln Val Ser Leu 355 360365 Thr Cys Leu Val Lys Gly Phe Tyr Pro Ser Asp Ile Ala Val Glu Trp 370375 380 Glu Ser Asn Gly Gln Pro Glu Asn Asn Tyr Lys Thr Thr Pro Pro Val385 390 395 400 Leu Asp Ser Asp Gly Ser Phe Phe Leu Tyr Ser Lys Leu ThrVal Asp 405 410 415 Lys Ser Arg Trp Gln Gln Gly Asn Val Phe Ser Cys SerVal Met His 420 425 430 Glu Ala Leu His Asn His Tyr Thr Gln Lys Ser LeuSer Leu Ser Pro 435 440 445 Gly Lys 450 50 213 PRT Artificial SequenceDescription of Artificial Sequence Light chain of high potency antibody.50 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 510 15 Asp Arg Val Thr Ile Thr Cys Ser Pro Ser Ser Arg Val Gly Tyr Met 2025 30 His Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 3540 45 Asp Thr Met Arg Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 5055 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 6570 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr85 90 95 Phe Gly Gly Gly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro100 105 110 Ser Val Phe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser GlyThr 115 120 125 Ala Ser Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg GluAla Lys 130 135 140 Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly AsnSer Gln Glu 145 150 155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser ThrTyr Ser Leu Ser Ser 165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr GluLys His Lys Val Tyr Ala 180 185 190 Cys Glu Val Thr His Gln Gly Leu SerSer Pro Val Thr Lys Ser Phe 195 200 205 Asn Arg Gly Glu Cys 210 51 450PRT Artificial Sequence Description of Artificial Sequence Heavy chainof high potency antibody. 51 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala LeuVal Lys Pro Thr Gln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser GlyPhe Ser Leu Ser Thr Pro 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln ProPro Gly Lys Ala Leu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Asp LysLys His Tyr Asn Pro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys AspThr Ser Lys Asn Gln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp ProAla Asp Thr Ala Thr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn PheTyr Phe Asp Val Trp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser SerAla Ser Thr Lys Gly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser SerLys Ser Thr Ser Gly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val LysAsp Tyr Phe Pro Glu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser GlyAla Leu Thr Ser Gly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln SerSer Gly Leu Tyr Ser Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser SerSer Leu Gly Thr Gln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 ProSer Asn Thr Lys Val Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220Lys Thr His Thr Cys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230235 240 Pro Ser Val Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile245 250 255 Ser Arg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser HisGlu 260 265 270 Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val GluVal His 275 280 285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn SerThr Tyr Arg 290 295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp TrpLeu Asn Gly Lys 305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys AlaLeu Pro Ala Pro Ile Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly GlnPro Arg Glu Pro Gln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu GluMet Thr Lys Asn Gln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly PheTyr Pro Ser Asp Ile Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln ProGlu Asn Asn Tyr Lys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser AspGly Ser Phe Phe Leu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser ArgTrp Gln Gln Gly Asn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu AlaLeu His Asn His Tyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 GlyLys 450 52 213 PRT Artificial Sequence Description of ArtificialSequence Light chain of high potency antibody. 52 Asp Ile Gln Met ThrGln Ser Pro Ser Thr Leu Ser Ala Ser Val Gly 1 5 10 15 Asp Arg Val ThrIle Thr Cys Ser Leu Ser Ser Arg Val Gly Tyr Met 20 25 30 His Trp Tyr GlnGln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Phe TyrLeu Ser Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly ThrGlu Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe AlaThr Tyr Tyr Cys Phe Gln Gly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly GlyGly Thr Lys Val Glu Ile Lys Arg Thr Val Ala Ala Pro 100 105 110 Ser ValPhe Ile Phe Pro Pro Ser Asp Glu Gln Leu Lys Ser Gly Thr 115 120 125 AlaSer Val Val Cys Leu Leu Asn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140Val Gln Trp Lys Val Asp Asn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150155 160 Ser Val Thr Glu Gln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser165 170 175 Thr Leu Thr Leu Ser Lys Ala Asp Tyr Glu Lys His Lys Val TyrAla 180 185 190 Cys Glu Val Thr His Gln Gly Leu Ser Ser Pro Val Thr LysSer Phe 195 200 205 Asn Arg Gly Glu Cys 210 53 450 PRT ArtificialSequence Description of Artificial Sequence Heavy chain of high potencyantibody. 53 Gln Val Thr Leu Arg Glu Ser Gly Pro Ala Leu Val Lys Pro ThrGln 1 5 10 15 Thr Leu Thr Leu Thr Cys Thr Phe Ser Gly Phe Ser Leu SerThr Pro 20 25 30 Gly Met Ser Val Gly Trp Ile Arg Gln Pro Pro Gly Lys AlaLeu Glu 35 40 45 Trp Leu Ala Asp Ile Trp Trp Asp Asp Lys Lys His Tyr AsnPro Ser 50 55 60 Leu Lys Asp Arg Leu Thr Ile Ser Lys Asp Thr Ser Lys AsnGln Val 65 70 75 80 Val Leu Lys Val Thr Asn Met Asp Pro Ala Asp Thr AlaThr Tyr Tyr 85 90 95 Cys Ala Arg Asp Met Ile Phe Asn Phe Tyr Phe Asp ValTrp Gly Gln 100 105 110 Gly Thr Thr Val Thr Val Ser Ser Ala Ser Thr LysGly Pro Ser Val 115 120 125 Phe Pro Leu Ala Pro Ser Ser Lys Ser Thr SerGly Gly Thr Ala Ala 130 135 140 Leu Gly Cys Leu Val Lys Asp Tyr Phe ProGlu Pro Val Thr Val Ser 145 150 155 160 Trp Asn Ser Gly Ala Leu Thr SerGly Val His Thr Phe Pro Ala Val 165 170 175 Leu Gln Ser Ser Gly Leu TyrSer Leu Ser Ser Val Val Thr Val Pro 180 185 190 Ser Ser Ser Leu Gly ThrGln Thr Tyr Ile Cys Asn Val Asn His Lys 195 200 205 Pro Ser Asn Thr LysVal Asp Lys Arg Val Glu Pro Lys Ser Cys Asp 210 215 220 Lys Thr His ThrCys Pro Pro Cys Pro Ala Pro Glu Leu Leu Gly Gly 225 230 235 240 Pro SerVal Phe Leu Phe Pro Pro Lys Pro Lys Asp Thr Leu Met Ile 245 250 255 SerArg Thr Pro Glu Val Thr Cys Val Val Val Asp Val Ser His Glu 260 265 270Asp Pro Glu Val Lys Phe Asn Trp Tyr Val Asp Gly Val Glu Val His 275 280285 Asn Ala Lys Thr Lys Pro Arg Glu Glu Gln Tyr Asn Ser Thr Tyr Arg 290295 300 Val Val Ser Val Leu Thr Val Leu His Gln Asp Trp Leu Asn Gly Lys305 310 315 320 Glu Tyr Lys Cys Lys Val Ser Asn Lys Ala Leu Pro Ala ProIle Glu 325 330 335 Lys Thr Ile Ser Lys Ala Lys Gly Gln Pro Arg Glu ProGln Val Tyr 340 345 350 Thr Leu Pro Pro Ser Arg Glu Glu Met Thr Lys AsnGln Val Ser Leu 355 360 365 Thr Cys Leu Val Lys Gly Phe Tyr Pro Ser AspIle Ala Val Glu Trp 370 375 380 Glu Ser Asn Gly Gln Pro Glu Asn Asn TyrLys Thr Thr Pro Pro Val 385 390 395 400 Leu Asp Ser Asp Gly Ser Phe PheLeu Tyr Ser Lys Leu Thr Val Asp 405 410 415 Lys Ser Arg Trp Gln Gln GlyAsn Val Phe Ser Cys Ser Val Met His 420 425 430 Glu Ala Leu His Asn HisTyr Thr Gln Lys Ser Leu Ser Leu Ser Pro 435 440 445 Gly Lys 450 54 213PRT Artificial Sequence Description of Artificial Sequence Light chainof high potency antibody. 54 Asp Ile Gln Met Thr Gln Ser Pro Ser Thr LeuSer Ala Ser Val Gly 1 5 10 15 Asp Arg Val Thr Ile Thr Cys Ser Leu SerSer Arg Val Gly Tyr Met 20 25 30 His Trp Tyr Gln Gln Lys Pro Gly Lys AlaPro Lys Leu Leu Ile Tyr 35 40 45 Asp Thr Arg Gly Leu Pro Ser Gly Val ProSer Arg Phe Ser Gly Ser 50 55 60 Gly Ser Gly Thr Glu Phe Thr Leu Thr IleSer Ser Leu Gln Pro Asp 65 70 75 80 Asp Phe Ala Thr Tyr Tyr Cys Phe GlnGly Ser Gly Tyr Pro Phe Thr 85 90 95 Phe Gly Gly Gly Thr Lys Val Glu IleLys Arg Thr Val Ala Ala Pro 100 105 110 Ser Val Phe Ile Phe Pro Pro SerAsp Glu Gln Leu Lys Ser Gly Thr 115 120 125 Ala Ser Val Val Cys Leu LeuAsn Asn Phe Tyr Pro Arg Glu Ala Lys 130 135 140 Val Gln Trp Lys Val AspAsn Ala Leu Gln Ser Gly Asn Ser Gln Glu 145 150 155 160 Ser Val Thr GluGln Asp Ser Lys Asp Ser Thr Tyr Ser Leu Ser Ser 165 170 175 Thr Leu ThrLeu Ser Lys Ala Asp Tyr Glu Lys His Lys Val Tyr Ala 180 185 190 Cys GluVal Thr His Gln Gly Leu Ser Ser Pro Val Thr Lys Ser Phe 195 200 205 AsnArg Gly Glu Cys 210 55 16 PRT Artificial Sequence Description ofArtificial SequenceHigh potency CDR sequence. 55 Asp Ile Trp Trp Asp GlyLys Lys Ser Tyr Asn Pro Ser Leu Lys Asp 1 5 10 15 56 10 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 56Leu Pro Ser Ser Arg Val Gly Tyr Met His 1 5 10 57 7 PRT ArtificialSequence Description of Artificial SequenceHigh potency CDR sequence. 57Asp Thr Phe Phe Leu Asp Ser 1 5 58 7 PRT Artificial Sequence Descriptionof Artificial SequenceHigh potency CDR sequence. 58 Asp Thr Arg Tyr GlnSer Ser 1 5 59 10 PRT Artificial Sequence Description of ArtificialSequenceLight Chain CDR reference sequence. 59 Lys Cys Gln Leu Ser ValGly Tyr Met His 1 5 10

What is claimed is:
 1. A high potency antibody, includingimmunologically active portions, fragments, or segments thereof, otherthan vitaxin and having a k_(on) of at least 2.5×10⁵ M⁻¹ s⁻¹.
 2. Thehigh potency antibody of claim 1 wherein said k_(on) is at least about5×10⁵ M⁻¹ s⁻¹.
 3. The high potency antibody of claim 1 wherein saidk_(on) is at least about 7.5×10⁵ M⁻¹ s⁻¹.
 4. The high potency antibodyof claim 1 wherein said antibody is a neutralizing antibody.
 5. The highpotency neutralizing antibody of claim 4 wherein said antibody hasspecificity for antigenic determinants found on microbes.
 6. The highpotency neutralizing antibody of claim 5 wherein said microbe isselected from the group consisting of viruses, bacteria and fungi. 7.The high potency neutralizing antibody of claim 5 wherein said microbeis a virus.
 8. The high potency neutralizing antibody of claim 7 whereinsaid virus is selected from the group respiratory syncytial virus (RSV)and parainfluenza virus (PIV).
 9. The high potency neutralizing antibodyof claim 1 wherein said antibody is specific for antigens found oncancer cells.
 9. The high potency neutralizing antibody of claim 1wherein said antibody has an affinity constant (K_(a)) of at least about10⁹ M⁻¹.
 10. The high potency antibody of claim 1 wherein said antibodyis specific for a toxic substance or a product of a toxic substance. 11.The high potency neutralizing antibody of claim 1 wherein said antibodyhas an affinity constant (K_(a)) of at least about 10⁹ M⁻¹.
 12. The highpotency neutralizing antibody of claim 1 wherein said antibody has anaffinity constant (K_(a)) of at least about 10¹⁰ M⁻¹.
 13. The highpotency neutralizing antibody of claim 1 wherein said antibody has anaffinity constant (K_(a)) of at least about 10¹¹ M⁻¹.
 14. The highpotency neutralizing antibody of claim 1 wherein said antibody has anEC₅₀ of less than 6.0 nM.
 15. The high potency neutralizing antibody ofclaim 1 wherein said antibody has an EC₅₀ of less than 3.0 nM.
 16. Thehigh potency neutralizing antibody of claim 1 wherein said antibody hasan EC₅₀ of less than 1.0 nM.
 17. The high potency neutralizing antibodyof claim 1, wherein said antibody comprises one or more high potencycomplementarity determining regions (CDR).
 18. The high potencyneutralizing antibody of claim 17, wherein said antibody comprises atleast 2 high potency CDRs.
 19. The high potency neutralizing antibody ofclaim 18, wherein said antibody comprises at least 4 high potency CDRs.20. The high potency neutralizing antibody of claim 19, wherein saidantibody comprises 6 high potency CDRs.
 21. The high potencyneutralizing antibody of claim 19, wherein said high potency CDRsconsist of one each of light chain CDRs L1 (CDR L1), L2 (CDR L2), and L3(CDR L3) and heavy chain CDRs H1 (CDR H1), H2 (CDR H2) and H3 (CDR H3).22. The high potency neutralizing antibody of claim 17, wherein saidhigh potency CDRs have amino acid sequences selected from the groupconsisting of SEQ ID NO: 11, 12, 13 and 56 for CDR L1, SEQ ID NO: 14,15, 16, 17, 18, 19, 20, 21, 22, 57 and 58 for CDR L2, SEQ ID NO: 23 forCDR L3, SEQ ID NO: 24 and 25 for CDR H1, SEQ ID NO: 26, 27, 28, 29, 30and 55 for CDR H2, SEQ ID NO: 31, 32, 33 and 34 for CDR H3.
 23. The highpotency neutralizing antibody of claim 1 wherein said antibody has aheavy chain amino acid sequence selected from the group consisting ofSEQ ID NO: 37, 39, 41, 45, 47, 49, 51 and 53, and a light chain aminoacid sequence selected from the group consisting of SEQ ID NO: 38, 40,42, 44, 46, 48, 50, 52 and
 54. 24. A process for producing a highpotency neutralizing antibody comprising: (a) producing a recombinantantibody, including immunologically active fragments thereof, comprisingheavy and light chain variable regions containing one or more frameworkand/or complementarity determining regions (CDRs) having preselectedamino acid sequences; (b) screening said recombinant antibodies for highassociation kinetic constant (k_(on)) when said antibody reacts in vitrowith a selected antigen; and (c) selecting antibodies with said highassociation kinetic constant (k_(on) ).
 25. The process of claim 24wherein said k_(on) is at least 3×10⁵ M⁻¹ s⁻¹.
 26. The process of claim24 wherein said k_(on) is at least 10⁶ M⁻¹ s⁻¹.
 27. The process of claim24 wherein the preselected amino acid sequence producing a high k_(on)is present in both framework region and at least one CDR region of theantibody.
 28. The process of claim 24 wherein the preselected amino acidsequence producing a high k_(on) is present in both framework region andat least two CDR regions of the antibody.
 29. The process of claim 24wherein the preselected amino acid sequence producing a high k_(on) ispresent in both framework region and at least four CDR regions of theantibody.
 30. The process of claim 24 wherein the preselected amino acidsequence producing a high k_(on) is present in both framework region andsix CDR regions of the antibody.
 31. The process of claim 24 whereinsaid antibody is further screened in step (b) for an affinity constantof at least 10⁹ M⁻¹.
 32. The process of claim 24 wherein said antibodyis further screened in step (b) for an affinity constant of at least10¹⁰ M⁻¹.
 33. The process of claim 24 wherein said antibody is furtherscreened in step (b) for an affinity constant of at least 10¹¹ M⁻¹. 34.The process of claim 24 wherein said high affinity constant is at least10¹⁰ M⁻¹ and said high association constant is at least 5×10⁵ M⁻¹ s⁻¹.35. A process for producing a high potency neutralizing antibodycomprising producing a recombinant antibody comprising heavy and lightchain variable regions containing framework and/or complementaritydetermining regions (CDR) wherein at least one CDR is a high k_(on) CDRand wherein the presence of said CDR results in a high k_(on).
 36. Theprocess of claim 35 wherein said recombinant high k_(on) antibodycomprises at least two high k_(on) CDRs.
 37. The process of claim 36wherein said recombinant high k_(on) antibody comprises at least fourhigh k_(on) CDRs.
 38. The process of claim 35 wherein said recombinanthigh k_(on) antibody comprises six high k_(on) CDRs and wherein saidhigh potency CDRs consist of one each of light chain CDRs L1 (CDR L1),L2 (CDR L2), and L3 (CDR L3) and heavy chain CDRs H1 (CDR H1), H2 (CDRH2) and H3 (CDR H3).
 39. The process of claim 35 wherein said k_(on) isat least 5×10⁵ M⁻¹ s⁻¹.
 40. The process of claim 35 wherein said k_(on)is at least 7.5×10⁵ M⁻¹ s⁻¹.
 41. The process of claim 35 wherein saidantibody also has an affinity constant (K_(a)) of at least 10⁹ M⁻¹. 42.The process of claim 35 wherein said antibody also has an affinityconstant (K_(a)) of at least 10¹⁰ M⁻¹.
 43. The process of claim 35wherein said antibody also has an affinity constant (K_(a)) of at least10¹¹ M⁻¹.
 44. A process for increasing the potency of an antibodycomprising selectively changing one or more amino acids within thevariable region framework and/or CDR regions of the antibody so as toincrease the measured k_(on) value of said antibody.
 45. The process ofclaim 44 wherein the amino acid changes are restricted to the CDRportions of said variable regions.
 46. The process of claim 44 whereinthe affinity of said antibody prior to said amino acid changes is atleast 10⁹ M⁻¹.
 47. The process of claim 44 wherein the affinity of saidantibody prior to said amino acid changes is at least 10¹⁰ M⁻¹.
 48. Theprocess of claim 44 wherein the affinity of said antibody prior to saidamino acid changes is at least 10¹¹ M⁻¹.
 49. The process of claim 44wherein the k_(on) value following said amino acid changes is at least5×10⁵ M⁻¹ sec⁻¹.
 50. The process of claim 44 wherein the k_(on) valuefollowing said amino acid changes is at least 10⁶ M⁻¹ sec⁻¹.
 51. Aprocess for preventing or treating a disease comprising administering toa patient at risk of such disease, or afflicted with such disease, atherapeutically effective amount of an antibody, or fragment thereof,selected from the group consisting of the antibodies of claims 1, 24, 35and
 44. 52. The process of claim 51 wherein the disease is caused by avirus.
 53. The process of claim 52 wherein said virus is selected fromthe group consisting of respiratory syncytial virus and parainfluenzavirus.
 54. The process of claim 51 wherein the antibody, or activefragment thereof, has a light chain variable region having the aminoacid sequence of SEQ ID NO. 35 and the heavy chain variable region hasthe amino acid sequence of SEQ ID NO.
 36. 55. The process of claim 51wherein said antibody is an Fab fragment.
 57. A high potencyneutralizing antibody having at least one light chain and at least oneheavy chain wherein said light chain is selected from the groupconsisting of SEQ ID NO: 38, 40, 42, 44, 46, 48, 50, 52 and 54 and whoseheavy chain is selected from the group consisting of SEQ ID NO: 37, 39,41, 43, 45, 47, 49, 51, and 53.